Improved documentation + fixed some typo's/spelling errors

[monkeyphysics]

I only last week found Hydrahon and started using it. As a new user, I relied heavily on the documentation and went through most of it.

This pull only features textual changes: some minor improvements to the documentation (that would have helped me had they been there when I went through the docs), and some fixed typo's and spelling errors.

[mario-deluna]

@monkeyphysics Thank you very much, documentation improvements are always very welcome!