Add Kuery docs and break search page into subsections (elastic#13074)

* Add Kuery docs and break search page into subsections

docs/discover/kuery.asciidoc

@@ -0,0 +1,115 @@
+[[kuery-query]]
+=== Kuery
+
+experimental[This functionality is experimental and may be changed or removed completely in a future release.]
+
+Kuery is a new query language built specifically for Kibana. It aims to simplify the search experience in Kibana
+and enable the creation of helpful features like auto-complete, seamless migration of saved searches, additional
+query types, and more. Kuery is a basic experience today but we're hard at work building these additional features on
+top of the foundation Kuery provides.
+
+Kueries are built with functions. Many functions take a field name as their first argument. Extremely common functions have shorthand notations.
+
+`is("response", 200)` will match documents where the response field matches the value 200.
+`response:200` does the same thing. `:` is an alias for the `is` function.
+
+Multiple search terms are separated by whitespace.
+
+`response:200 extension:php` will match documents where response matches 200 and extension matches php.
+
+All terms must match by default. The language supports boolean logic with and/or operators. The above query is equivalent to `response:200 and extension:php`.
+
+We can make terms optional by using `or`.
+
+`response:200 or extension:php` will match documents where response matches 200, extension matches php, or both.
+
+By default, `and` has a higher precedence than `or`.
+
+`response:200 and extension:php or extension:css` will match documents where response is 200 and extension is php OR documents where extension is css and response is anything.
+
+We can override the default precedence with grouping.
+
+`response:200 and (extension:php or extension:css)` will match documents where response is 200 and extension is either php or css.
+
+Terms can be inverted by prefixing them with `!`.
+
+`!response:200` will match all documents where response is not 200.
+
+Entire groups can also be inverted.
+
+`response:200 and !(extension:php or extension:css)`
+
+Some query functions have named arguments.
+
+`range("bytes", gt=1000, lt=8000)` will match documents where the bytes field is greater than 1000 and less than 8000.
+
+Quotes are generally optional if your terms don't have whitespace or special characters. `range(bytes, gt=1000, lt=8000)`
+would also be a valid query.
+
+[NOTE]
+============
+Terms without fields will be matched against all fields. For example, a query for `response:200` will search for the value 200
+in the response field, but a query for just `200` will search for 200 across all fields in your index.
+============
+
+==== Function Reference
+
+[horizontal]
+Function Name::  Description
+
+and:: 
+Purpose::: Match all given sub-queries
+Alias::: `and` as a binary operator
+Examples::: 
+* `and(response:200, extension:php)`
+* `response:200 and extension:php`
+
+or::
+Purpose::: Match one or more sub-queries
+Alias::: `or` as a binary operator
+Examples::: 
+* `or(extension:css, extension:php)`
+* `extension:css or extension:php`
+
+not::
+Purpose::: Negates a sub-query
+Alias::: `!` as a prefix operator
+Examples:::
+* `not(response:200)` 
+* `!response:200`
+
+is::
+Purpose::: Matches a field with a given term
+Alias::: `:`
+Examples::: 
+* `is("response", 200)`
+* `response:200`
+
+range::
+Purpose::: Match a field against a range of values.
+Alias::: `:[]`
+Examples::: 
+* `range("bytes", gt=1000, lt=8000)`
+* `bytes:[1000 to 8000]`
+Named arguments:::
+* `gt` - greater than
+* `gte` - greater than or equal to
+* `lt` - less than
+* `lte` - less than or equal to
+
+exists::
+Purpose::: Match documents where a given field exists
+Examples::: `exists("response")`
+
+geoBoundingBox::
+Purpose::: Creates a geo_bounding_box query
+Examples:::
+* `geoBoundingBox("coordinates", topLeft="40.73, -74.1", bottomRight="40.01, -71.12")` (whitespace between lat and lon is ignored)
+Named arguments:::
+* `topLeft` - the top left corner of the bounding box as a "lat, lon" string
+* `bottomRight` - the bottom right corner of the bounding box as a "lat, lon" string
+
+geoPolygon::
+Purpose::: Creates a geo_polygon query given 3 or more points as "lat, lon"
+Examples::: 
+* `geoPolygon("geo.coordinates", "40.97, -127.26", "24.20, -84.375", "40.44, -66.09")`

docs/discover/search.asciidoc

@@ -1,10 +1,10 @@
 [[search]]
 == Searching Your Data
 You can search the indices that match the current index pattern by entering
-your search criteria in the Query bar. You can perform a simple text search,
-use the Lucene https://lucene.apache.org/core/2_9_4/queryparsersyntax.html[
-query syntax], or use the full JSON-based {ref}/query-dsl.html[Elasticsearch
-Query DSL].
+your search criteria in the Query bar. You can use the Lucene
+https://lucene.apache.org/core/2_9_4/queryparsersyntax.html[
+query syntax], the full JSON-based {ref}/query-dsl.html[Elasticsearch
+Query DSL] or Kuery, an experimental new query language built specifically for Kibana.
 
 When you submit a search request, the histogram, Documents table, and Fields
 list are updated to reflect the search results. The total number of hits
@@ -19,6 +19,17 @@ To search your data, enter your search criteria in the Query bar and
 press *Enter* or click *Search* image:images/search-button.jpg[] to submit
 the request to Elasticsearch.
 
+[NOTE]
+===========
+By default, Kibana will accept either the Lucene query syntax or the
+Elasticsearch Query DSL in the Query bar. In order to use the new Kuery
+language you must enable language switching in *Management > Advanced Settings*
+via the `search:queryLanguage:switcher:enable` option. You can also change the 
+default language with the `search:queryLanguage` setting.
+===========
+
+[[lucene-query]]
+=== Lucene Query Syntax
 * To perform a free text search, simply enter a text string. For example, if
 you're searching web server logs, you could enter `safari` to search all
 fields for the term `safari`.
@@ -36,37 +47,40 @@ status codes, you could enter `status:[400 TO 499]`.
 codes and have an extension of `php` or `html`, you could enter `status:[400 TO
 499] AND (extension:php OR extension:html)`.
 
-NOTE: These examples use the Lucene query syntax. You can also submit queries
-using the Elasticsearch Query DSL. For examples, see
-{ref}/query-dsl-query-string-query.html#query-string-syntax[query string syntax]
-in the Elasticsearch Reference.
+For more detailed information about the Lucene query syntax, see the
+{ref}/query-dsl-query-string-query.html#query-string-syntax[Query String Query]
+docs.
 
-[float]
-[[save-search]]
-=== Saving a Search
+NOTE: These examples use the Lucene query syntax. When lucene is selected as your
+query language you can also submit queries using the {ref}/query-dsl.html[Elasticsearch Query DSL].
+
+include::kuery.asciidoc[]
+
+[[save-open-search]]
+=== Saving and Opening Searches
 Saving searches enables you to reload them into Discover and use them as the basis
 for <<visualize, visualizations>>. Saving a search saves both the search query string
 and the currently selected index pattern.
 
+==== Saving a Search
 To save the current search:
 
 . Click *Save* in the Kibana toolbar.
 . Enter a name for the search and click *Save*.
 
 You can import, export and delete saved searches from *Management/Kibana/Saved Objects*.
 
-[float]
-[[load-search]]
-=== Opening a Saved Search
+==== Opening a Saved Search
 To load a saved search into Discover:
 
 . Click *Open* in the Kibana toolbar.
 . Select the search you want to open.
 
 If the saved search is associated with a different index pattern than is currently
-selected, opening the saved search also changes the selected index pattern.
+selected, opening the saved search changes the selected index pattern. The query language
+used for the saved search will also be automatically selected.
+
 
-[float]
 [[select-pattern]]
 === Changing Which Indices You're Searching
 When you submit a search request, the indices that match the currently-selected
@@ -77,7 +91,6 @@ different index pattern.
 For more information about index patterns, see <<settings-create-pattern,
 Creating an Index Pattern>>.
 
-[float]
 [[autorefresh]]
 === Refreshing the Search Results
 As more documents are added to the indices you're searching, the search results