jj-git-remote-{add,set-url}: add pages

[AgamAgarwal]

Checklist

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR contains at most 5 new pages.
• The PR is authored by me, or has been human-reviewed if it was created with AI or machine translation software.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known): 0.44.0
• Reference issue: Let's document: jj (Jujutsu) #17040

[Managor]

These are exactly 8 examples. Please fill the base page before creating subcommand pages.

[TheRootDaemon]

These are exactly 8 examples. Please fill the base page before creating subcommand pages.

This thought occurred to me as well, but there is already a base page for jj-git-remote.

I thought of consolidating the 4 sub pages(in this PR) into a single page
and since there was a base page already I just let it be.

What do you think ??

[Managor]

Every example in the original page is present in this PR

[AgamAgarwal]

Removed the pages for jj-git-remote-{list,remove,rename} since they had one example each, which were already present in the base jj-git-remote page.

Left jj-git-remote-{add,set-url} since they had more examples.

[Managor]

You can merge the rest of these examples into jj-git-remote.md. There are only 3 new examples here and the base page has 5