doc: consistent formatting on python manual section

No material changes to docs, but trying to sanitize them for consistent
readability prior to looking at #75837.

- Use `*` for lists instead of `-`. I have no opinion one way or the other, but
  the latter was only used in 1-2 places.
- Pad the code blocks with whitespace.
- Wrap to 80 characters, except for a few 1-liners that were only slightly over.