Clean up some docs

* Consistent line endings in rippled-example.cfg
* Rewrite CodingStyle.md. Get down to top priorities

These are some pretty trivial non-code changes.
- The config file was just bugging me, and confusing my editor. No non-whitespace changes.
- A discussion of CodingStyle.md pointed out that it was out of date and incorrect, except for the "Formatting" section. Rather than chasing a moving target, it was simplified to a few core ideas that can be built on as things evolve.