chore: add missing open scaffolding files

[airscripts]

Hey there @retrohacking!
As promised I'm here with a first welcome pull request.

Since I don't know where the project is leading as of now, I thought to start off with some open scaffolding files, in order to make the repository more welcoming to newcomers willing to contribute.

In detail, I've added the following files and entities:

• CODEOWNERS: this one serves the purpose of assigning to you automatically everything related to this repository, such as this pull request for example;
• Issue Templates: these files are a pretty cool addition for whenever someone files a new issue;
• CODE_OF_CONDUCT: I've used a standard guideline from the Contributor Covenant that serves well every time;
• CONTRIBUTING: this file will contain the contribution guidelines to be followed in order to contribute to this project. Right now it's very simple so that you can keep it as is or enhance with a workflow you like;
• LICENSE: an open project without a license is not really open in terms of usability and redistribution. I've chosen GPL-3.0 which is one of the most fantastic licenses for pure open source software.

Aside of this, inside the README, I've dropped a simple table of contents.
It's a nice addition to reach the categories without the need of searching them out visually.

And this wraps everything up, I think.
Let me know, wherever you want, if you are willing to make this project grow with automatic tests, documentation or even code robustness just to name a few.

P.S.: One thing, for example, that it's not stated is the minimum Python version needed to run this project and some other cool stuff related, for increasing the experience in the usage of this amazing idea that you've developed!

[retrohacking]

Thank you for your availability! When I'll have new ideas for this project, I'll surely make you know, so you can help me if you like 😄
However, I've merged your pull request, thank you!