docs: Mention anndataR in interoperability section

[Bisaloo]

• Closes
• Tests added

• Release note not necessary because: documentation change only

I opted to list it at the top of the list as it is the official scverse project so it probably makes sense to give it a bit of extra visibility.

cc @Zethson, as discussed on Zulip.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.60%. Comparing base (581b93c) to head (40a78e5).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2466   +/-   ##
=======================================
  Coverage   85.60%   85.60%           
=======================================
  Files          49       49           
  Lines        7671     7671           
=======================================
  Hits         6567     6567           
  Misses       1104     1104           

[Zethson]

Thank you!