Added server.defaultRoute (#9080)

Backports PR #9075

**Commit 1:**
Added server.defaultRoute

* Original sha: cb565e1
* Authored by Gabriel Moskovicz <gmoskovicz@gmail.com> on 2016-11-15T14:32:23Z
* Committed by GitHub <noreply@github.com> on 2016-11-15T14:32:23Z

**Commit 2:**
Update settings.asciidoc

* Original sha: 1de0297
* Authored by Gabriel Moskovicz <gmoskovicz@gmail.com> on 2016-11-15T15:53:52Z
* Committed by GitHub <noreply@github.com> on 2016-11-15T15:53:52Z

docs/setup/settings.asciidoc

@@ -14,6 +14,7 @@ you'll need to update your `kibana.yml` file. You can also enable SSL and set a
  to Kibana. This setting cannot end in a slash (`/`).
 `server.maxPayloadBytes:`:: *Default: 1048576* The maximum payload size in bytes for incoming server requests.
 `server.name:`:: *Default: "your-hostname"* A human-readable display name that identifies this Kibana instance.
+`server.defaultRoute:`:: *Default: "/app/kibana"* This setting specifies the default route when opening Kibana. You can use this setting to modify the landing page when opening Kibana.
 `elasticsearch.url:`:: *Default: "http://localhost:9200"* The URL of the Elasticsearch instance to use for all your
 queries.
 `elasticsearch.preserveHost:`:: *Default: true* When this setting’s value is true Kibana uses the hostname specified in