[DOCS] Add examples and descriptions for script APIs (#3613) (#3621)

(cherry picked from commit f39e614)

Author: lcawl

docs/overlays/elasticsearch-shared-overlays.yaml

@@ -170,6 +170,11 @@ actions:
       # S
         - name: script
           x-displayName: Script
+          description: >
+            Use the script support APIs to get a list of supported script contexts and languages.
+            Use the stored script APIs to manage stored scripts and search templates.
+          externalDocs:
+            url: https://www.elastic.co/guide/en/elasticsearch/reference/master/modules-scripting.html
         - name: search
           x-displayName: Search
         - name: search_application