Remove out-of-date external compatibility section from hdf_store docs
- [x] closes #35419 (Replace xxxx with the GitHub issue number)
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.


The code in this section is just wrong (in multiple ways – see issue), and the suggestion from @TomAugspurger was to just remove this section. Kinda late follow up 😅
Thanks @ivirshup nice cleanup!