Here comes a short checklist we need to follow GitHub.
We have chosen MIT as standard license. All repos must have a LICENSE.md.
We have standard README which you can copy and use.
Always but always think about showability of your work.
The easy yet effective way is to release a functional demo, e.g. deploy to Heroku or some place like this. Then share a link with your colleagues.
In most cases, you learn about new frameworks and you craft a repo as an example. Well, go ahead and open source it! :)
We have standard .gitignore which you can copy and use.
The best documentation is the codebase itself, for it's our shared language! :)
Therefore, write clean code, make sure it contains easy to understand comments, and also have easy to browse commit messages. Nicely written working code can beat all world of documentation!
See few links, good to read: