Document keys in releases json

[pbabinca]

I'd like to test one of the scripts (koji-create-package-in-release) but I'm missing docs how to create one and what is actually required:

$ koji-create-package-in-release --owner pbabinca foo bar
releng_sop.common.ConfigError: Couldn't find config file 'default.json' in following locations:
/home/pbabinca/.config/releng-sop/environments
/etc/releng-sop/environments

[csomh]

There is a quick start guide here < http://releng-sop.readthedocs.io/en/latest/quickstart.html> I am really not sure whether this is enough or not, so any feedback on how it could be improved is welcome.