[DOCS] terminate_after is not experimental anymore

we are relying on terminate_after more and more, replaced the limit filter with it and soon it will also replace the search_exists api. At that point we should make it a stable api rather than experimental.

Closes #14183

docs/reference/search/count.asciidoc

@@ -73,8 +73,7 @@ not. Defaults to `true`.
 |`analyze_wildcard` |Should wildcard and prefix queries be analyzed or
 not. Defaults to `false`.
 
-|`terminate_after` |experimental[The API for this feature may change in the future]
-The maximum count for each shard, upon
+|`terminate_after` |The maximum count for each shard, upon
 reaching which the query execution will terminate early.
 If set, the response will have a boolean field `terminated_early` to
 indicate whether the query execution has actually terminated_early.

docs/reference/search/request-body.asciidoc

@@ -79,7 +79,6 @@ And here is a sample response:
 
 `terminate_after`::
 
-    experimental[The API for this feature may change in the future]
     The maximum number of documents to collect for each shard,
     upon reaching which the query execution will terminate early. If set, the
     response will have a boolean field `terminated_early` to indicate whether

docs/reference/search/uri-request.asciidoc

@@ -91,8 +91,7 @@ scores and return them as part of each hit.
 within the specified time value and bail with the hits accumulated up to
 that point when expired. Defaults to no timeout.
 
-|`terminate_after` |experimental[The API for this feature may change in the future]
-The maximum number of documents to collect for
+|`terminate_after` |The maximum number of documents to collect for
 each shard, upon reaching which the query execution will terminate early.
 If set, the response will have a boolean field `terminated_early` to
 indicate whether the query execution has actually terminated_early.