`useful-resource` label

In fair few of our repos, people reading through the READMEs will often see something like this:

A large number of open issues.

This can give the impression that the repo is unmaintained or that there are many problems yet to be fixed with the material, but in reality, we use issues a little differently to most people.

Whereas some of the issues are genuine open questions or bugs, the vast majority are either suggestions for things that could be added to the readme or good articles/videos related to the repo.

For example in the [`learn-elixir`](https://github.com/dwyl/learn-elixir/issues) repo, looking at the first 11 issues (most recent), there are 7 articles/videos that are interesting for people learning elixir, one _question_ on the material and 3 suggested additions to the README.


It's not exactly 74 bugs!

I propose we create a label (in some form of green) to indicate that something is available for reading and a possible addition to the README, making it clear it's not a bug or misinformation.

The best I could come up with was a `Good resource`label but I'd welcome any more descriptive label names! Defined as 'Denotes an article or video that's a good resource on this topic but is tangential or more advanced than the README'