Document that we are open for PRs against the doc somewhere

[ghudgins]

Motivation

I need to see how to contribute changes to the docs, from the docs

[vorburger]

I just assumed that you were open when I sent you #160 ... 😆

But could be neat is to directly have one of Edit pages right there on the generated HTML pages which takes you straight to the Markdown on GitHub.

Just to illustrate, for example, on (my) https://docs.enola.dev/use/ in the upper right hand corner there is an "edit page" sort of icon which does this. (The static site generator which I happen use on that project offers this feature built-in.)