Couldn't find a field in "Configuration" docs

**What steps did you take:**
During the TGIK session, while attempting to build with Docker, Josh Rosso was looking up the meaning of a field (`path`) in the configuration in the docs.

**What happened:**
He couldn't find it without the help of a Carvel team member. He scrolled immediately down to the "Docker" section... and looked for the definition of `path` (which is actually part of `Source`)... but that wasn't listed there.

**What did you expect:**
I expected he could have easily located the meaning of any field in the configuration schema.

**Anything else you would like to add:**
It seemed to be unclear that each subsection in this page describes an inner portion of the configuration file.

Possibly, if that hierarchy was more obvious (e.g. a link to jump up to a higher level), Josh might have gotten there.