Doc updates (#791)

Updates for better displaying the documentation in the website.

docs/index.asciidoc

@@ -1,51 +1,12 @@
 = @elastic/elasticsearch
 
-The official Node.js client for Elasticsearch.
-
-== Features
-* One-to-one mapping with REST API.
-* Generalized, pluggable architecture.
-* Configurable, automatic discovery of cluster nodes.
-* Persistent, Keep-Alive connections.
-* Load balancing (with pluggable selection strategy) across all available nodes.
-* TypeScript support out of the box.
-
-== Install
-[source,sh]
-----
-npm install @elastic/elasticsearch
-----
-By default the latest version of the module will be installed, which is the same version of the current release of Elasticsearch. +
-If you need to work with older versions of Elasticsearch, you should install the same version of the client as well. +
-For example, if you are using Elasticsearch `v6.5.4`, you will need the client `v6`, and you can easily do that with `npm install @elastic/elasticsearch@6`.
-
-== Usage
-[source,js]
-----
-const { Client } = require('@elastic/elasticsearch')
-const client = new Client({ node: 'http://localhost:9200' })
-
-// promise API
-const result = await client.search({
-  index: 'my-index',
-  body: { foo: 'bar' }
-})
-
-// callback API
-client.search({
-  index: 'my-index',
-  body: { foo: 'bar' }
-}, (err, result) => {
-  if (err) console.log(err)
-})
-----
-
-== Reference
-* Client configuration
-* Client usage
-* API methods
-* TypeScript support
-* Extend the client
-* Breaking changes from old client
-* Authentication
-* Child client
+include::introduction.asciidoc[]
+include::usage.asciidoc[]
+include::configuration.asciidoc[]
+include::reference.asciidoc[]
+include::breaking-changes.asciidoc[]
+include::authentication.asciidoc[]
+include::child.asciidoc[]
+include::extend.asciidoc[]
+include::typescript.asciidoc[]
+include::examples/index.asciidoc[]