(PE-3622) Tweak config format and fix bug in example

This commit makes a slight tweak to our "canonical" config examples,
to use a colon before the definition of a map.  This keeps us a
little closer to the standard JSON format.

I also found a bug in the ring example code and fixed it.
Merge pull request #22 from cprice404/maint/master/PE-3304-tweak-config-format-and-fix-bug-in-example

(PE-3622) Tweak config format and fix bug in example