[DOCS] Add links to Fleet APIs

Author: lcawl

docs/reference/fleet/fleet-multi-search.asciidoc

@@ -5,6 +5,12 @@
 <titleabbrev>Fleet multi search</titleabbrev>
 ++++
 
+.New API Reference
+[sidebar]
+--
+For the most up-to-date API details, refer to {api-es}/group/endpoint-fleet[{fleet} APIs].
+--
+
 Executes several <<fleet-search,fleet searches>> with a single API request.
 
 The API follows the same structure as the <<search-multi-search, multi search>> API. However,

docs/reference/fleet/fleet-search.asciidoc

@@ -5,6 +5,12 @@
 <titleabbrev>Fleet search</titleabbrev>
 ++++
 
+.New API Reference
+[sidebar]
+--
+For the most up-to-date API details, refer to {api-es}/group/endpoint-fleet[{fleet} APIs].
+--
+
 The purpose of the fleet search api is to provide a search api where the search
 will only be executed after provided checkpoint has been processed and is visible
 for searches inside of Elasticsearch.

docs/reference/fleet/index.asciidoc

@@ -2,6 +2,12 @@
 [[fleet-apis]]
 == Fleet APIs
 
+.New API Reference
+[sidebar]
+--
+For the most up-to-date API details, refer to {api-es}/group/endpoint-fleet[{fleet} APIs].
+--
+
 TIP: For the {kib} {fleet} APIs, see the
 {fleet-guide}/fleet-api-docs.html[Fleet API Documentation].