DOC: capitalize Python as proper noun
- [ ] closes #xxxx
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Thanks - can you also fix this in other doc pages, such as doc/source/ecosystem.rst and doc/source/user_guide/cookbook.rst? There's a few other places where it appears uncapitalised > Thanks - can you also fix this in other doc pages, such as doc/source/ecosystem.rst and doc/source/user_guide/cookbook.rst? There's a few other places where it appears uncapitalised

@MarcoGorelli sure thing! I ran:

```
grep python -r *
grep jupyter -r *
```

in the `doc/source/` directory to find instances and changed them. I also found some other random capitalizations along the way.

I didn't touch anything in the `whatsnew/` directory. @MarcoGorelli hopefully got them now! Thanks for the suggestions. (Side note, just realized I can't spell my branches right and caused me some confusion while making edits 😅) thanks @erictleung 