Autoupdate documentation with coqdoc to 7c6b4f6

Generated with `make html` on commit:

commit 7c6b4f618706144d23d259abb6897cb7a3760d9a
Author: Jason Gross <jgross@mit.edu>
Date:   Sun Sep 15 16:40:59 2013 -0400

    Get rid of some useless '∘ 1'