DOC: get_subsets do not return masked subset state

[pllim]

Description

This pull request is a direct follow-up of #2087 .

Change log entry

• Is a change log needed? If yes, is it added to CHANGES.rst? If you want to avoid merge conflicts,
  list the proposed change log here for review and add to CHANGES.rst before merge. If no, maintainer
  should add a no-changelog-entry-needed label.

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[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (82bebcb) 91.78% compared to head (05d92ec) 91.78%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2184   +/-   ##
=======================================
  Coverage   91.78%   91.78%           
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  Files         147      147           
  Lines       16262    16262           
=======================================
  Hits        14926    14926           
  Misses       1336     1336           

Impacted Files	Coverage Δ
jdaviz/app.py	92.92% <ø> (ø)

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[kecnry]

Is there anywhere in RTD that needs a disclaimer as well? Or do we not introduce get_subsets there at all?

[pllim]

@kecnry , I didn't see any mention of get_subsets in the docs.