ES Mapping - Doc Page

Context :

In order to release the Elasticsearc Mapping PoC, we need documentation  

To Do :

• Update search doc to include information about PoC, but in such as way as it can be removed is the PoC is inconclusive 

• Define the landing page for the link in ticket
  Alerte in predicate https://jira.nuxeo.com/browse/NXS-6506
  The link underneath the title in the Elastic search mapping page https://jira.nuxeo.com/browse/NXS-6508

For the text:

"This field uses the default mapping, you may need to configure Elasticsearch mapping to use advanced search features View Documentation Here" 

• If the Feature is Nuxeo only, the doc page should not be in the Doc navigation  

AC :

• As a user, I can access Documentation that explains broadly the idea of ES Mapping, and how it interacts with the PP  
• As a user general, I can understand what the PoC does and its limitations