Fix breakage in ndfc_rest_rediscover + doc improvements

Changes:

We renamed the role ndfc_rest_rediscover, but didn't rename the role's directory :-(

Added links in the main README.md to each of the roles

Added documentation for the msd_fabrics dictionary

Several other minor cleanup changes

Full Changelog: allenrobel/ndfc-roles@v0.1.3-alpha...v0.1.4-alpha