Cherrypick doc changes into 5.2 (#3495, #3507, #3512) (#3529)

* Add edits for load and socket metricset docs

* Remove step to set default index pattern

* Add new config options to the decode_json_fields processor docs

* Run make update

libbeat/docs/dashboards.asciidoc

@@ -96,11 +96,10 @@ PS > scripts\import_dashboards.exe -es https://xyz.found.io -user user -pass pas
 After importing the dashboards, launch the Kibana web interface by pointing your browser
 to port 5601. For example, http://127.0.0.1:5601[http://127.0.0.1:5601].
 
-If Kibana shows a `No default index pattern` warning, you must select or create
-an index pattern to continue. To resolve the issue, select the
-predefined +{beatname_lc}-*+ index pattern and set it as the default.
+On the *Discover* page, make sure that the predefined +{beatname_lc}-*+ index
+pattern is selected to see {beatname_uc} data.
 
-image:./images/kibana-created-indexes.png[Kibana configured indexes]
+image:./images/kibana-created-indexes.png[Discover tab with index selected]
 
 To open the loaded dashboards, go to the *Dashboard* page and click *Open*.
 Select the dashboard that you want to open. 

libbeat/docs/processors-config.asciidoc

@@ -353,6 +353,8 @@ processors:
      fields: ["field1", "field2", ...]
      process_array: false 
      max_depth: 1
+     target:
+     overwrite_keys: false
 -----------------------------------------------------
 
 The `decode_json_fields` processor has the following configuration settings:
@@ -361,6 +363,13 @@ The `decode_json_fields` processor has the following configuration settings:
 `process_array`:: (Optional) A boolean that specifies whether to process
 arrays. The default is false.
 `max_depth`:: (Optional) The maximum parsing depth. The default is 1.
+`target`:: (Optional) The field under which the decoded JSON will be written. By
+default the decoded JSON object replaces the string field from which it was
+read. To merge the decoded JSON fields into the root of the event, specify
+`target` with an empty value (`target:`).
+`overwrite_keys`:: (Optional) A boolean that specifies whether keys that already
+exist in the event are overwritten by keys from the decoded JSON object. The
+default value is false.
 
 [[drop-event]]
 === drop_event

libbeat/docs/processors.asciidoc

@@ -6,7 +6,7 @@
 //// Use the appropriate variables defined in the index.asciidoc file to
 //// resolve Beat names: beatname_uc and beatname_lc.
 //// Use the following include to pull this content into a doc file:
-//// include::../../libbeat/docs/filtering.asciidoc[]
+//// include::../../libbeat/docs/processors.asciidoc[]
 //////////////////////////////////////////////////////////////////////////
 
 You can define processors in your configuration to process events before they

metricbeat/docs/fields.asciidoc

@@ -6398,7 +6398,7 @@ type: ip
 
 example: 192.0.2.1 or 2001:0DB8:ABED:8536::1
 
-Remote IP address. This can be an IPv4 or IPv6 address
+Remote IP address. This can be an IPv4 or IPv6 address.
 
 
 [float]

metricbeat/module/system/load/_meta/docs.asciidoc

@@ -1,4 +1,4 @@
-=== system load MetricSet
+=== System Load Metricset
 
 The System `load` metricset provides load statistics.
 

metricbeat/module/system/socket/_meta/docs.asciidoc

@@ -1,37 +1,39 @@
-=== system socket MetricSet
+=== System Socket Metricset
 
-WARNING: This functionality is in beta and is subject to change. It should be
-deployed in production at your own risk.
+beta[]
 
 This metricset is available on Linux only and requires kernel 2.6.14 or newer.
 
-The system socket metricset reports an event for each new TCP socket that it
-sees. It does this by polling the kernel to get a dump of all sockets. So using
-a short polling interval with this metricset is important to not miss short
-lived connections. You can configure a period specifically for this module by
-declaring it separately from other system metricsets.
+The system `socket` metricset reports an event for each new TCP socket that it
+sees. It does this by polling the kernel periodically to get a dump of all
+sockets. You set the polling interval by configuring the `period` option.
+Specifying a short polling interval with this metricset is important to avoid
+missing short-lived connections. For example: 
 
 [source,yaml]
 ---
 metricbeat.modules:
 - module: system
   metricsets: [cpu, memory]
-- module: system
-  metricsets: [socket]
+- module: system 
+  metricsets: [socket] <1>
   period: 1s
 ---
 
+<1> You can configure the `socket` metricset separately to specify a different
+`period` value than the other metricsets. 
+
 The metricset reports the process that has the socket open. In order to provide
-this information Metricbeat must be running as root. It needs to be root to read
-the file descriptor information of other processes.
+this information, Metricbeat must be running as root. Root access is also
+required to read the file descriptor information of other processes.
 
-A reverse lookup can be performed by the metricset on the remote IP and the
-returned hostname will be added to the event and cached. The is disabled by
-default and can be enabled through the configuration.  If a hostname is found
-then the eTLD+1 (effective top-level domain plus one level) value will also be
-added to the event.
+You can configure the metricset to perform a reverse lookup on the remote IP,
+and the returned hostname will be added to the event and cached. If a hostname
+is found, then the eTLD+1 (effective top-level domain plus one level) value will
+also be added to the event. Reverse lookups are disabled by default. 
 
-The full configuration for the metricset is shown below with its defaults.
+The following example shows the full configuration for the metricset along with
+the defaults.
 
 [source,yaml]
 ---

metricbeat/module/system/socket/_meta/fields.yml

@@ -32,7 +32,7 @@
       type: ip
       example: 192.0.2.1 or 2001:0DB8:ABED:8536::1
       description: >
-        Remote IP address. This can be an IPv4 or IPv6 address
+        Remote IP address. This can be an IPv4 or IPv6 address.
 
     - name: remote.port
       type: long