* Adding get snapshot status API docs.
* Adding more fields and a link to the new page.
* Adding missing spaces in TESTRESPONSES
* Adding more parameters and making some edits.
* Marking snapshot as optional
* Marking repository as optional
* Add data type for stats
* Add data type for shard_stats
* Incorporating review feedback.
* Lots of review feedback incorporated.
* Fixing tests to unbreak CI builds.
* Changing indices to index.
