[6.0] Region map settings clarifications (#14893) (#15422)

* Region map settings clarifications (#14893)

Improve documentation

* use fully qualified paths

docs/setup/settings.asciidoc

@@ -79,15 +79,11 @@ The minimum value is 100.
 
 [[regionmap-settings]] `regionmap`:: Specifies additional vector layers for use in <<regionmap, Region Map>> visualizations.
 Each layer object points to an external vector file that contains a geojson FeatureCollection.
-The file must use the [WGS84 coordinate reference system](https://en.wikipedia.org/wiki/World_Geodetic_System) and only include polygons. 
+The file must use the https://en.wikipedia.org/wiki/World_Geodetic_System[WGS84 coordinate reference system] and only include polygons. 
 If the file is hosted on a separate domain from Kibana, the server needs to be CORS-enabled so Kibana can download the file.
-The url field also serves as a unique identifier for the file.
-Each layer can contain multiple fields to indicate what properties from the geojson features you want to expose.
-The field.description is the human readable text that is shown in the Region Map visualization's field menu.
-An optional attribution value can be added as well.
 The following example shows a valid regionmap configuration.
 
-    regionmap:
+    regionmap:      
       layers:
          - name: "Departments of France"
            url: "http://my.cors.enabled.server.org/france_departements.geojson"
@@ -97,6 +93,13 @@ The following example shows a valid regionmap configuration.
                 description: "Full department name"
               - name: "INSEE"
                 description: "INSEE numeric identifier"
+
+`regionmap.layers[].name:`:: Mandatory. A description of the map being provided.
+`regionmap.layers[].url:`:: Mandatory. The location of the geojson file as provided by a webserver.
+`regionmap.layers[].attribution:`:: Optional. References the originating source of the geojson file.
+`regionmap.layers[].fields[]:`:: Mandatory. Each layer can contain multiple fields to indicate what properties from the geojson features you wish to expose. The example above shows how to define multiple properties.
+`regionmap.layers[].fields[].name:`:: Mandatory. This value is used to do an inner-join between the document stored in Elasticsearch and the geojson file. e.g. if the field in the geojson is called `Location` and has city names, there must be a field in Elasticsearch that holds the same values that Kibana can then use to lookup for the geoshape data.
+`regionmap.layers[].fields[].description:`:: Mandatory. The human readable text that is shown under the Options tab when building the Region Map visualization.
 
 `server.basePath:`:: Enables you to specify a path to mount Kibana at if you are running behind a proxy. This only affects
  the URLs generated by Kibana, your proxy is expected to remove the basePath value before forwarding requests