[python/r] Update docstrings for domain argument to create

[johnkerl]

Issue and/or context: As tracked on issue #2407 / [sc-51048].

Note that the intended Python and R API changes are all agreed on and finalized as described in #2407.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.94%. Comparing base (0ce5ac9) to head (062008d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3396      +/-   ##
==========================================
+ Coverage   85.85%   85.94%   +0.09%     
==========================================
  Files          55       55              
  Lines        6199     6199              
==========================================
+ Hits         5322     5328       +6     
+ Misses        877      871       -6     

Flag	Coverage Δ
python	85.94% <ø> (+0.09%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
python_api	85.94% <ø> (+0.09%)	⬆️
libtiledbsoma	∅ <ø> (∅)

[mojaveazure]

LGTM on the R side, please remember to update the docs with devtools::document()

[johnkerl]

@ryan-williams I'd love a second pair of 👀 for the Python side -- if you haven't time, that's fine, I'll need to merge by say mid-day tomorrow

[ryan-williams]

Couple questions about the Python docstr

[johnkerl]

#3398 tracks the CI break which was not caused by this docstring-only PR.