Update contributing

[Rubix982]

This PR adds more friendlier instructions for getting git running and cloning the repository, as a step by step followup.

It also,

1. Adds instructions how to give branches a good, easier to understand name
2. Capitalizes some headings, to make them consistent with the rest of the format
3. Adds a small text at the add of ## Sending Content Directly, to give people a quick idea

I do not know why it also shows commit from the update-code-of-conduct branch. You can make an example by,

1. Switching to a new branch
2. Committing there
3. Push branch to remote
4. Switch to new branch
5. Make other commits
6. Push newest branch to remote