Document kind of tag that is created from the UI

What does this MR do?

When creating a tag from the UI without a message, we create a lightweight tag, versus an annotated tag when a message was provided.

https://git-scm.com/book/en/v2/Git-Basics-Tagging

This was brought up in #31318 (comment 226622081)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content