The list of domains in the docs is somewhat outdated and I think it would be useful if we could take advantage of the PyPI trove classifiers and create a Framework :: Sphinx :: Domain, similar to Framework :: Sphinx :: Extension. But first we need to have the classifier approved and created using these guidelines:

• New Framework classifiers should be created if they are "notable;" and
• They will be of immediate use to existing projects (in other words, no creating classifiers simply in anticipation of future uses)
  We understand that "notability" is subjective and we'd appreciate help judging that.

As to the other guideline ('immediate use to existing projects'), it's been suggested that

• Requestors can demonstrate this by providing links to 10 or more existing PyPI projects that have expressed a desire to use the classifier; or
• Another way to demonstrate this would be to have 10 or more other project maintainers submit comments on the requesting issue about their desire to use the classifier.

If you maintain a Sphinx domain and think a Framework :: Sphinx :: Domain would be useful for helping people find your domain as well as the greater Sphinx ecosystem, please leave a comment expressing interest in using the classifier with a link to the package that you maintain to help with the approval process.