Achieve 100% doc coverage [WIP]

see: https://github.com/rspec/rspec-core/issues/1334

currently:
```
Files:          48
Modules:        31 (   21 undocumented)
Classes:        50 (   27 undocumented)
Constants:      27 (   25 undocumented)
Methods:       388 (  202 undocumented)
 44.56% documented