[Doc bug]Jira User Server feature supports editing a username

Issue Summary

Old Jira versions do not maintain external ids, and the old Jira User Servers do not support editing a username.
However, the current Jira User Server feature version supports editing a username due to maintaining external ids.

From these facts, the following description in the document is out of date.

(Jira)Create, edit, or remove a user

> Edit a username, full name, or email address
> If you are using your Jira instance as a Jira User Server for other applications, (e.g., Confluence), you will not be able to use this feature. If you aren’t sure about this, check under User Management > Jira User Server to confirm that no external applications have been configured to use Jira as a Crowd Server.

Steps to Reproduce

See (Jira)Create, edit, or remove a user

Expected Results

Removing the second bullet point of the warnings(The following section).

(Jira)Create, edit, or remove a user

> Edit a username, full name, or email address
> If you are using your Jira instance as a Jira User Server for other applications, (e.g., Confluence), you will not be able to use this feature. If you aren’t sure about this, check under User Management > Jira User Server to confirm that no external applications have been configured to use Jira as a Crowd Server.

Actual Results

The warnings in the document are remains from older Jira version.

Workaround

Ignore this warnings in the document.