Changes:
* Moves `Retrieve selected fields` to its own page and adds a title abbreviation.
* Adds existing script and stored fields content to `Retrieve selected fields`
* Adds a xref for `Retrieve selected fields` to `Search your data`
* Adds related redirects and updates existing xrefs
Moves the search sort docs from the deprecated 'Request Body Search'
page to a new subpage of 'Run a search'.
No substantive changes were made to the content.
Generally we don't advocate for using `stored_fields`, and we're interested in
eventually removing the need for this parameter. So it's best to avoid using
stored fields in our docs examples when it's not actually necessary.
Individual changes:
* Avoid using 'stored_fields' in our docs.
* When defining script fields in top-hits, de-emphasize stored fields.
