REST API change logs should be updated with the changes due to JSWSERVER-21156

Issue Summary

In Jira 8.20.7, we introduced a change on these REST API endpoints due to this bug report:

user/assignable/search
user/assignable/multiProjectSearch
user/viewissue/search
user/mention/search

Where these endpoints don't support "startAt" parameter anymore,
and in these endpoints, the "maxResults" parameter cannot exceed 100.

This is breaking customers' scripts and integrations.

Steps to Reproduce

Upgrade to Jira 8.20.7

Expected Results

https://confluence.atlassian.com/jiracore/jira-8-20-rest-api-change-log-1101931823.html should be updated with this information

Actual Results

No updates on page https://confluence.atlassian.com/jiracore/jira-8-20-rest-api-change-log-1101931823.html 

The release notes have been updated with changes Issues resolved in 8.20.7 as part of fix done in JRASERVER-73679

Workaround

Modify scripts to not use the "StartAt" parameter