Update doc URLs from readthedocs.org/com to app.readthedocs.org/com (#12251)
This is on all instances, I didn't want to tune and content otherwise.
There are a few sections we can return to here, this update was just the
first step.
- Refs #12127
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:books: Documentation previews :books:
- User's documentation (`docs`):
https://docs--12251.org.readthedocs.build/12251/
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- Developer's documentation (`dev`):
https://dev--12251.org.readthedocs.build/12251/
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