CHROMIUM: add link to our blocker documentation

As people migrate files between packages, it seems the use of
blockers is missed.  Add some links to the error message.

TEST=emerging a package w/blockers shows a nice error

Change-Id: I775d57b2a7298f9c3d6039dbb4c2922a5eb1d35d
Reviewed-by: Chris McDonald <>
Tested-by: Mike Frysinger <>
Commit-Queue: Mike Frysinger <>
1 file changed