Previously these were only linked in a circuitous way rather than being
available from the top level API documentation and "Put Lifecycle" API docs.
This makes them slightly easier to find for a user.
* [DOCS] ILM API Ref edits
* [DOCS] Fixed endpoint for DELETE policy.
* [DOCS] Removed comparison to setting index.lifecycle.name to null.
* [DOCS] Fixed xrefs to explain API.
Lee Hinman
lcawl
Tal Levy
debadair
Gordon Brown
Colin Goodheart-Smithe