Add "Search Documentation" block to /documentation

Problem/Motivation

At /community there was a block to search the documentation. #944332: Remove "Search Documentation" block from /community is removing it.

Maybe it should be added to /documentation

Proposed resolution

Fix the search so it is usable and accessible, then add it to /documentation

Remaining tasks

Make sure the documentation working group wants it (instead of trying to re-use the search in the header maybe with a documentation only default setting).

It should not be added until the problems with it are fixed.

• #2376023: Change 'Documentation Search Block' CSS
• #2376009: Fix accessibility of "Search Documentation" block
• #2376011: Improve usability of "Search Documentation" block

User interface changes

Documentation before

After

https://searchdocs-drupal.redesign.devdrupal.org/community
https://searchdocs-drupal.redesign.devdrupal.org/documentation

Documentation after (search block)
@todo put screenshot here after the css fixes from @kattekrab #25-27 are in a patch and on the dev site.

Documentation after (search results)
@todo put screenshot here after the css fixes from @kattekrab #25-27 are in a patch and on the dev site.

API changes

None.