Fixed error message

Seems like this should be "be", not "by"
Merge pull request #1270 from awentzonline/patch-1

Fixed error message
Added a section for "pip" itself in the usage.
The top of the usage page needed something to hold the
orphaned General and Index options, otherwise it's disorientating.
Fix the test which is still looking for the by typo
Make Wheel respect --root
some extra logging and options tests
Ensure that --root continues to work with Wheels
Merge pull request #1272 from dstufft/fix-pip-wheel

Make Wheel respect --root