Remove extra dashes in a flag name in the user guide
Use consistent dashes in the user guide

We were using a mixture of "&ndash;&ndash;" and "--". We now
consistently use "--", which has the advantage that copy/pasting
flags will work.
The help flag is --help, not -help; fixes #8005
Fix syntax in some code in the user guide; fixes #8007
Merge branch 'master' of http://darcs.haskell.org/ghc