add doc for how to configure a metric with Prometheus

[lust4life]

@lust4life I've added a section in the README so people know how to configure a metric with Prometheus. Perhaps you could add one of the samples from this thread there?

Originally posted by @haf in https://github.com/logary/logary/pull/395#issuecomment-479073948

[haf]

I created a CD pipeline with google cloud builder and next.js; just edit the docs in ./docs and commit, and it'll be automatically deployed at https://logary.tech/ 2 minutes later.

[haf]

The site is now live and up to date with all docs that we have!

[64J0]

The site is down for me @haf

[haf]

Hey @64J0 ; yes, Logary as a project has undergone a lot of changes. I'm looking for help to do documentation for this library.

[64J0]

Maybe we could start using Nacara to build the next version of the docs.

[haf]

Yes possibly, or preferrably a generator that is mainstream and supports a library version selector.

[haf]

https://docusaurus.io/ is warmly recommended by some of my CTO friends

[haf]

We'll be documenting Logary-JS with this as well.