[DOCS] Adds Breaking changes from old client to Introduction. (#1453)

docs/breaking-changes.asciidoc

@@ -1,5 +1,5 @@
 [[breaking-changes]]
-== Breaking changes coming from the old client
+=== Breaking changes coming from the old client
 
 If you were already using the previous version of this client – the one you used 
 to install with `npm install elasticsearch` – you will encounter some breaking 
@@ -7,7 +7,7 @@ changes.
 
 
 [discrete]
-=== Don’t panic!
+==== Don’t panic!
 
 Every breaking change was carefully weighed, and each is justified. Furthermore, 
 the new codebase has been rewritten with modern JavaScript and has been 
@@ -15,7 +15,7 @@ carefully designed to be easy to maintain.
 
 
 [discrete]
-=== Breaking changes
+==== Breaking changes
 
 *  Minimum supported version of Node.js is `v8`.
 
@@ -212,7 +212,7 @@ client.transport.request({
 ----
 
 [discrete]
-=== Talk is cheap. Show me the code.
+==== Talk is cheap. Show me the code.
 
 You can find a code snippet with the old client below followed by the same code 
 logic but with the new client.

docs/index.asciidoc

@@ -18,5 +18,4 @@ include::transport.asciidoc[]
 include::typescript.asciidoc[]
 include::reference.asciidoc[]
 include::examples/index.asciidoc[]
-include::breaking-changes.asciidoc[]
 include::helpers.asciidoc[]

docs/introduction.asciidoc

@@ -4,6 +4,9 @@
 This is the official Node.js client for {es}. This page gives a quick overview 
 about the features of the client.
 
+Refer to <<breaking-changes,this page>> for breaking changes coming from the old 
+client.
+
 
 [discrete]
 === Features
@@ -189,3 +192,6 @@ npm install esmaster@github:elastic/elasticsearch-js
 ----
 WARNING: This command installs the master branch of the client which is not
 considered stable.
+
+
+include::breaking-changes.asciidoc[]