Autoupdate documentation with coqdoc to 219aad9

Generated with `make html` on commit:

commit 219aad982aabae44367f06f31cde46d6a9db3f36
Author: Jason Gross <jgross@mit.edu>
Date:   Tue Sep 3 22:51:51 2013 -0400

    Add associativity of NTComposeT