Command Tutorials

[sovdeeth]

Added two command tutorials.

The first is a slightly updated version of #18, and the second is a new tutorial aimed at users who are very new to Skript.
It goes over only the basics of command to avoid throwing too much information at a new users, but tries to explain enough to give a good grounding in the concept.
The first tutorial picks up the slack and has a lot more information, but presented with less explanation and more examples. It's meant to be more like a reference page that users of all skill levels can refer back to if they forget bits and pieces, or want to learn a bit more about the more niche things commands feature.

Feedback very much appreciated! The main thing I'd like is feedback about the pacing and structure of the introductory tutorial. Oh, and how inter-site links should be formatted.

See the formatted files here:
https://github.com/sovdeeth/skript-docs/blob/new-command-tutorial/commands.md
https://github.com/sovdeeth/skript-docs/blob/new-command-tutorial/command-basics.md