Fix typos and improve spelling in messages

[twelho]

When installing the project, I noticed a couple of typos in the printed messages. While fixing those, I also did a pass over the other prompts with some wording clarifications. Thanks to messages.sh consolidating all prompts, this was quite easy to do, kudos for this design.

[KwadFan]

Thanks for your contribution, but I messed it up.
Replaced by #145

Hopefully you will do another PR so that you get on contributors list.

Regards Kwad

[twelho]

Hopefully you will do another PR so that you get on contributors list.

It's already up, feel free to review #137 :)

[twelho]

Thanks for your contribution, but I messed it up.

Also, as a helpful tip, you can fix this kind of situation where you've added extra commits to a branch/pull request quite easily. When you're on the branch, just run git rebase -i HEAD~n, where n is the number of commits that you want to work with, so in this case 3, as there are three commits in this PR now. An editor opens with one commit per line, now you can just remove the lines for the unwanted commits. Save the file, close the editor, and you're done! Push your changes with git push -f (the -f is needed since you're modifying already pushed commits).

Finally, copying someones contribution into a new commit authored by someone else (i.e., it doesn't preserve attribution), is a bad practice. If the PR gets messed up, you can just ping the author to run git push -f from their side, which instantly cleans everything up. Mistakes happen, but you can be sure the PR authors are here to help you get their work merged :)