Backports PR #9690
**Commit 1:**
[tribe] Init docs
* Original sha: 42e59dbbe8
* Authored by Jonathan Budzenski <jon@jbudz.me> on 2016-12-28T17:23:21Z
**Commit 2:**
[docs] Init es client section
* Original sha: 92ee7e12a5
* Authored by Jonathan Budzenski <jon@jbudz.me> on 2016-12-29T17:15:55Z
**Commit 3:**
[docs] Link to client api, move client library docs to core development section
* Original sha: deafe5a435
* Authored by Jonathan Budzenski <jon@jbudz.me> on 2017-01-11T20:27:56Z
**Commit 4:**
[docs] Add tribe server settings
* Original sha: a5c322912e
* Authored by Jonathan Budzenski <jon@jbudz.me> on 2017-01-11T20:51:35Z
**Commit 5:**
[tribe] Link to elasticsearch tribe docs
* Original sha: d94ff6f934
* Authored by Jonathan Budzenski <jon@jbudz.me> on 2017-01-11T20:56:40Z
**Commit 6:**
[tribe] Document which nodes server configuration points towards
* Original sha: ecfff93ae6
* Authored by Jonathan Budzenski <jon@jbudz.me> on 2017-01-11T21:14:47Z
**Commit 7:**
[docs] Add index link to elasticsearch clients section
* Original sha: a0e92c3a22
* Authored by Jonathan Budzenski <jon@jbudz.me> on 2017-01-11T22:22:14Z
* docs: kibana developer docs
This is the beginning of developer-focussed docs for Kibana. The content
is mostly pulled directly from the old wiki in the github repo.
* docs: known plugins for 5.x
