[docs] add wait_for guide

[pikaninja]

Summary

This pr adds the wait_for guide in the documentation. This was done in conjunction with HayBaleAv. I believe there's a few odd wording in this, any feedback would be appreciated

Checklist

• [ ] If code changes were made then they have been tested.
  • [ ] I have updated the documentation to reflect the changes.
• [ ] This PR fixes an issue.
• [ ] This PR adds something new (e.g. new method or parameters).
• [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed)
• [x] This PR is not a code change (e.g. documentation, README, ...)

[mirnovov]

It might be a good idea to include basic instructions on using wait_for for multiple things simultaneously, as in the multiple wait_for tag on the discord server. Though of course, including the proviso that it's a more advanced topic when mentioning it.

[pikaninja]

It might be a good idea to include basic instructions on using wait_for for multiple things simultaneously, as in the multiple wait_for tag on the discord server. Though of course, including the proviso that it's a more advanced topic when mentioning it.

i did consider adding this, but i felt it was a bit too jank and confusing to add to the guide, idk though

[AbstractUmbra]

Oh, one last thing for now.

Could the file be moved to docs/guide/topics/wait_for.rst to match the rest?