Document Spirit a little more clearly

[Gastove]

In particular: why fork and vendor it? What have you changed?

[marikaswanberg]

Is there a particular place we should have documentation about this?

[Gastove]

Given your use of your wiki, I'd probably write the documentation there, then link to it from your swrrt new readme (probably something like, "Spirit is a modern Python based forum... forum application, which we have forked; our fork is , notes on the decision to fork ". Could do it as a footnote instead of a clause at the end of the sentence? Something around like that.