add wrangler cli subcommand documentation for ai models

[bghira]

Summary

Add a new page for the wrangler ai models subcommand.

I'm not sure how to do the changelog portion (i found the guidelines, heh), or how to ensure this page is included in docs build.

NOTE: This requires the wrangler cli pull request here

Screenshots (optional)

Documentation checklist

• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.