Update "Tag name" help text on Edit Release page

What does this MR do?

Addresses feedback from the UX review by @rverissimo on this change: !18033 (comment 236499045)

Specifically, this MR updates the hint text under the "Tag name" field from:

Choose an existing tag, or create a new one

to:

Changing a release's tag is only supported using the Releases API. More information

The "More infomation" link will point to https://docs.gitlab.com/ee/api/releases/#update-a-release

Screenshots

Before:

After:

Responsive behavior:

Related

#26016 (closed)