Improve region map documentation

docs/management/advanced-options.asciidoc

@@ -54,6 +54,7 @@ when necessary.
 `visualization:colorMapping`:: Maps values to specified colors within visualizations.
 `visualization:loadingDelay`:: Time to wait before dimming visualizations during query.
 `visualization:dimmingOpacity`:: When part of a visualization is highlighted, by hovering over it for example, ths is the opacity applied to the other elements. A higher number means other elements will be less opaque.
+`visualization:regionmap:showWarnings`:: Whether the region map show a warning when terms cannot be joined to a shape on the map.
 `csv:separator`:: A string that serves as the separator for exported values.
 `csv:quoteValues`:: Set this property to `true` to quote exported values.
 `history:limit`:: In fields that have history, such as query inputs, the value of this property limits how many recent

docs/visualize/regionmap.asciidoc

@@ -26,10 +26,12 @@ Configure a _Terms_ aggregation. The term is the _key_ that is used to join the
 ==== Options
 
 ===== Layer Settings
-- *Vector map*: select from a list of vector maps. This list includes the maps that are hosted by the © [Elastic Maps Service](https://www.elastic.co/elastic-maps-service),
+- *Vector map*: select from a list of vector maps. This list includes the maps that are hosted by the © https://www.elastic.co/elastic-maps-service[Elastic Maps Service],
 as well as your self-hosted layers that are configured in the *config/kibana.yml* file. To learn more about how to configure Kibana
 to make self-hosted layers available, see the <<regionmap-settings,regionmap settings>> documentation.
-- *Join field*: this is the property from the selected vector map that will be used to join on the terms in your terms-aggregation.
+- *Join field*: this is the property from the selected vector map that will be used to join on the terms in your terms-aggregation. 
+When terms cannot be joined to any of the shapes in the vector layer because there is no exact match in the vector layer, Kibana will display a warning.
+To turn of these warnings, go to *Management/Kibana/Advanced Settings* and set `visualization:regionmap:showWarnings` to `vefalse`.
 
 ===== Style Settings
 - *Color Schema*: the color range used to color the shapes.

src/core_plugins/kibana/ui_setting_defaults.js

@@ -147,7 +147,7 @@ export function getUiSettingDefaults() {
     },
     'visualization:regionmap:showWarnings': {
       value: true,
-      description: 'Should the vector map show a warning when terms cannot be joined to a shape on the map.'
+      description: 'Whether the region map show a warning when terms cannot be joined to a shape on the map.'
     },
     'visualization:colorMapping': {
       type: 'json',