My first reaction was "every project on github can't be repeating how-to-use-github in the readme". But then I thought, well what's important here is to say how this particular project prefers to handle collaboration. That is, via forking rather than simple branching on a common repo. So maybe it would be worth just saying that here, instead of "make a github account". Say "this project is using the fork-and-pull-request model, even for SIL developers". And then follow with your existing link in the next paragraph.

(Note, the Bloom team found that when people got into git-related messes, it was because of this forking model. I gave us no benefit, just another layer of git-complexity for folks to trip over. So I no longer favor it when we have a team working on a project, with few if any outside contributions, when using git (we do it with hg projects, where no additional complexity is involved in this model).