Add documentation for Forgejo CI Actions runner #369

Content-wise, this is a nice "bridge" / introduction, but it's kind of leaving me confused. Maybe this sentence should be rewritten. "in different environments" is confusing me a bit. Rephrasing "how much you care about security" to "security needs" may also be better.

"how much you care about security" is a bit disorienting, as it insinuates that the infrastructure may be more prone to compromise if the wrong decision is taken, without much guidance as to how to achieve an optimal setup.

Here's two examples that I would build on top of:
Depending on your setup and your security needs, there is a wide variety of options for deploying [...]
There are various methods for deploying a Runner, choosing the right one depends on your setup and your security needs.

Why? Also, it would be cool if you could consistently capitalize names of tools like "docker" -> "Docker".

This could work as an admonition. (warning)

Would probably rewrite this to drop Recently; it's not relevant here.

Nit: different indentation

nit: the correct language tag for this is console: https://stackoverflow.com/a/49004070

@linusg That is not true in the syntax highlighter or markdown formatter the documentation is using. Applying console instead of bash breaks the syntax highlighting.

bash is valid even in the given context (GitHub Markdown format), you'll find the citations if you scroll in the replies or other answers in the page you linked.

It is valid, sure, but semantically not correct :)

I don't know what highlighter the docs use, but here on Forgejo console yields better results (first is console, second is bash):

$ command
output
$ another command

$ command
output
$ another command

likewise

likewise

I doubt the $ here are part of the output? looks like a prompt, I'd definitely avoid that.

likewise

likewise (I'll let you find the rest yourself :))

nit: indentation is four spaces here

nit: indentation