Update REST API docs for activities (#11691)

Current REST API documentation for activities is outdated. Since we have
automatically generated documentation for activity types on the Audit
activities page, with all the necessary details I think it's a good idea
to link REST API docs to this one.

REST API docs will have a description of what will be returned with
example and specific information about each activity type can be found
on the Audit activities page, which is always up-to-date.

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [ ] Changes file added for user-visible changes in `changes/` or
`orbit/changes/`.
See [Changes
files](https://fleetdm.com/docs/contributing/committing-changes#changes-files)
for more information.
- [ ] Documented any API changes (docs/Using-Fleet/REST-API.md or
docs/Contributing/API-for-contributors.md)
- [ ] Documented any permissions changes
- [ ] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [ ] Added support on fleet's osquery simulator `cmd/osquery-perf` for
new osquery data ingestion features.
- [ ] Added/updated tests
- [ ] Manual QA for all new/changed functionality
  - For Orbit and Fleet Desktop changes:
- [ ] Manual QA must be performed in the three main OSs, macOS, Windows
and Linux.
- [ ] Auto-update manual QA, from released version of component to new
version (see [tools/tuf/test](../tools/tuf/test/README.md)).

docs/Using-Fleet/REST-API.md

@@ -425,23 +425,7 @@ This is the callback endpoint that the identity provider will use to send securi
 ### List activities
 
 Returns a list of the activities that have been performed in Fleet as well as additional meta data
-for pagination. The following types of activity are included:
-
-- Created pack
-- Edited pack
-- Deleted pack
-- Applied pack with fleetctl
-- Created policy
-- Edited policy
-- Deleted policy
-- Applied policy with fleetctl
-- Created saved query
-- Edited saved query
-- Deleted saved query
-- Applied query with fleetctl
-- Ran live query
-- Created team - _Available in Fleet Premium_
-- Deleted team - _Available in Fleet Premium_
+for pagination. For a comprehensive list of activity types and detailed information, please see [Audit activities](https://fleetdm.com/docs/using-fleet/audit-activities) page.
 
 `GET /api/v1/fleet/activities`