Documentation lacking some non-obvious details

[jimdigriz]

Unless you know Lua, using this project is more difficult to use than it should be.

It needs to be mentioned in the documentation that some of the variables, such as $ngo_domain, are non-optional and need to be set, at least to the empty string otherwise you get a traceback where lua complains about calling len() on a nil value.

More subtle is how to deal with lua ssl certificate verify error: (20: unable to get local issuer certificate), which is caused by use of resty.http and thus you need to provide:

lua_ssl_trusted_certificate /etc/ssl/certs/ca-certificates.crt;