* Move fix common cluster issues to troubleshooting
* Include fix common cluster issues in the troubleshooting doc
* [DOCS] Remove extra include from How-To
Co-authored-by: Deb Adair <debadair@elastic.co>
Revises the current 'How to avoid oversharding' docs to incorporate
information from our [shard sizing blog post][0].
Changes:
* Streamlines introduction
* Adds "Things to remember" section to describe how shards work
* Adds "Guidelines" section based on blog tips
* Creates a "Fix an oversharded cluster" section
[0]: https://www.elastic.co/blog/how-many-shards-should-i-have-in-my-elasticsearch-cluster
This commit corrects the grammar in a list in the how-to docs; namely,
the word "and" was missing preceding the final element in a list.
Relates #22663
This moves the "Performance Considerations for Elasticsearch Indexing" blog post
to the reference guide and adds similar recommendations for tuning disk usage
and search speed.
