* wip

* Service Accounts - add beta documentation

* consistent names

* fix test

* Update service accounts overview and token creation files.

* Rename get service tokens to get service credentials

* fix tests

* Changes for create and get service tokens.

* Changes for get token creds, delete token, clear token cache, and token auth.

* add manage_service_account privilege to list

* List service accounts APIs

* Move xpack setting to Security API page, plus other cleanup.

* Shorten secret tokens in examples, add cross links, plus other cleanup.

* Clarifying parameter descriptions.

* Clarify language for authenticating with a token.

* Tweaks

* Typo fix

* Adding redirects to work around CI build checks

* Revert "Adding redirects to work around CI build checks"

This reverts commit 20a1b53591fee9cf80d352818572f47f8c637cd7.

* Remove redirects that were implemented to satisfy CI checks in master branch

* Move note about not supporting basic auth

* Clarify what service accounts are specifically for

* Apply suggestions from code review

Co-authored-by: Tim Vernum <tim@adjective.org>

* Addressing review feedback

* tweak

* Improve doc tests

* fix test

Co-authored-by: Adam Locke <adam.locke@elastic.co>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
Co-authored-by: Tim Vernum <tim@adjective.org>