Document support for deep linking types
Document support for deep linking types

Closes INTEROP-6324
flag=none

Test Plan
- run the doc:api rake task
- navigate to /doc/api/file.content_item.html
- verify new documentation is clear
- verify all new links work

Change-Id: I5ffe5981a5a88db5ee7846d708a78c9c73d8c700
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/259786
Reviewed-by: Xander Moffatt <27f70fe194da423604e6e0a63a3de19814736fa9@instructure.com>
Reviewed-by: Wagner Goncalves <1386d52ba3130eb1a5647e5b47f1073537d5ef43@instructure.com>
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Product-Review: Karl Lloyd <4c8060af93345c2cc416ee6aa55bceec4e5cc9d4@instructure.com>
QA-Review: Weston Dransfield <e9203059795dc94e28a8831c65eb7869e818825e@instructure.com>

sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms