Add a comment about communication padding widths.
Remove reference to 'n' distribution

... from the main text.
Fix the first example.
Merge pull request #73 from enthought/feature/communication-padding-constraint

Add a comment about communication padding widths.
Remove quotes around "undistributed".
Merge pull request #74 from enthought/feature/no-n-disttype

Remove the 'n' dist_type
Merge branch 'master' into feature/size-constraint