[DOCS] Add redirects for authentication and migration guide (#1634)

* [DOCS] Add redirects for authentication and migration guide

* Update auth refs

Author: jrodewig

docs/basic-config.asciidoc

@@ -48,8 +48,7 @@ node: {
 |`auth`
 a|Your authentication data. You can use both basic authentication and
 {ref}/security-api-create-api-key.html[ApiKey]. +
-See https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/current/auth-reference.html[Authentication]
-for more details. +
+See <<authentication,Authentication>> for more details. +
 _Default:_ `null`
 
 Basic authentication:

docs/connecting.asciidoc

@@ -6,14 +6,14 @@ This page contains the information you need to connect and use the Client with
 
 **On this page**
 
-* <<auth-reference, Authentication options>>
+* <<authentication, Authentication options>>
 * <<client-usage, Using the client>>
 * <<client-faas-env, Using the Client in a Function-as-a-Service Environment>>
 * <<client-connect-proxy, Connecting through a proxy>>
 * <<client-error-handling, Handling errors>>
 * <<product-check, Automatic product check>>
 
-[[auth-reference]]
+[[authentication]]
 [discrete]
 === Authentication
 

docs/index.asciidoc

@@ -19,3 +19,4 @@ include::typescript.asciidoc[]
 include::reference.asciidoc[]
 include::examples/index.asciidoc[]
 include::helpers.asciidoc[]
+include::redirects.asciidoc[]

docs/redirects.asciidoc

@@ -0,0 +1,17 @@
+["appendix",role="exclude",id="redirects"]
+= Deleted pages
+
+The following pages have moved or been deleted.
+
+[role="exclude",id="auth-reference"]
+== Authentication
+
+This page has moved. See <<client-connecting>>.
+
+[role="exclude",id="breaking-changes"]
+== Breaking changes
+
+For information about migrating from the legacy elasticsearch.js client to the
+new Elasticsearch JavaScript client, refer to the
+https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/7.17/breaking-changes.html[7.17
+JavaScript client migration guide].