Tutorial on yml configs

Is there any tutorial on bit more advanced yml syntax?
I am trying to create a per developer stack so each developer has their own environment.
I can see some samples on env.config.yml and syntaxes such as self:service and {opt:X}. But find it bit difficult to understand.

I couldn’t find any tutorial explaining those syntax. Could you please share, if you know any good place to learn those yml configurations?

Thanks!