Improved notes and added per class examples for accessor extensions
- [ ] closes #49202 
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).


Thanks for the pull request, but it appears to have gone stale and the checks are not all passing. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.