Documentation fixes, mostly for embedded.

* Refresh of embedded usgae docs for 2.2.
* Small tweaks to Cypher docs.
* Increasing wait time for indexes in neo4j-graphgist.
* Minor cleanup in docs for tx endpoint.
* Minor cleanup in docs for neo4j-import.
Merge pull request #3633 from nawroth/2.2-docs-fixes

Documentation fixes, mostly for embedded.