Fixed bug in ACL2-Doc browser.

Added explicit targets for books/Makefile in GNUmakefile.

Updated doc.lisp to reflect changes in
/Users/kaufmann/acl2/devel/books/system/doc/acl2-doc.lisp.


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1145 5d84a466-a78b-0930-a311-59b22171a541