Add small docs about xlsxwriter in user guide
- [x ] closes #27356
- [ ] tests added / passed
  - Not needed.  Just a doc change
- [ ] passes `black pandas`
  - Not needed.  Just a doc change
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
  - Not needed.  Just a doc change
- [ ] whatsnew entry
  - Not needed.  Just a doc change