DOC: Fix capitalization of the word pandas in the docs
- [x] closes #32316 
- [x] tests added / passed
- [x] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

As stated in the referred issue, _pandas_ reference in the docs should be standardised to pandas, not *pandas* or Pandas.

I've only changed the references in `doc/source/development/*.rst` for now, to see if the changes are okay or not