DOC: Fix capitalization among headings in documentation files (#32550)
Following #32978 and #32944.

Headers updated for the following files:
```
- [ ] doc/source/getting_started/comparison/comparison_with_stata.rst
- [ ] doc/source/getting_started/intro_tutorials/01_table_oriented.rst
- [ ] doc/source/getting_started/tutorials.rst
- [ ] doc/source/reference/arrays.rst
- [ ] doc/source/reference/window.rst
- [ ] doc/source/user_guide/boolean.rst
```