Hints for install errors - could go in README

[eperitus]

If you get the error:

src/cmds/serve.go:5:3: no required module provides package github.com/kellegous/pork: go.mod file not found in current directory or any parent directory; see 'go help modules'
make: *** [bin/serve] Error 1

You can run: go env -w GO111MODULE=auto

If you get an error about a particular version of sass not being found, you can run:
sudo gem install sass -v3.2.12

These hints could go in the README if enough people are hitting them.