While making a pull request against the core NodeBB project is of course not something you can just do on a whim, did you know that we've also allowed our docs portal to accept hacktoberfest pull requests too?
More reading: what is hacktoberfest anyway?
Making updates to docs pays for itself in dividends, because not only does it mean your knowledge is passed-on, it helps other people who may run into the same issue!
Our docs repo is here → https://github.com/NodeBB/docs
It doesn't take much to contribute, most of the files are just plain markdown. You can even edit it from within GitHub itself!