(MAINT) Minor improvements to the config examples in docs
(MAINT) Minor improvements to the config examples in docs

This commit fills out the text around some of the examples in the
`authorization-config.md` to hopefully make it a little more obvious
where each element of the config is specified relative to other elements
in the config.

camlow325/trapperkeeper-authorization,masterzen/trapperkeeper-authorization,puppetlabs/trapperkeeper-authorization