Attempt to clean up `Parent Selectors`, removed somewhat duplicated section/example (already in `Nested Rules`), minor reformatting in both files.
Added `Named Parameters` section, #44.
`Named Parameters`: extended example.
Merge pull request #48 from seven-phases-max/master

Minor clean up and reformatting in `Parent Selectors` and `Nested Rules`.
Merge pull request #49 from seven-phases-max/named-parameters

Documents "Named Parameters".