Where can I find the old mupx documentation?

I have to fix an error in an old app that still uses mupx for deployment. I ran into an error and am looking fro the old mupx documentation. But I cannot find the repo anymore. Does anyone know if it still exists or if there is a fork of the repo somewhere?

BTW: my deployment breaks since it isn’t compatible with the latest Xcode version. Thus, I want to make a server-only build. I am looking for a way to configure mupx for this (using meteor build --server-only). Another option would be to force Meteor to use the older Xcode I have on my PC. But I don’t know how to do this either.