Updated :doc acl2-doc to clarify about replacement of spaces by underscores in topic names.

git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1159 5d84a466-a78b-0930-a311-59b22171a541

Changes to support recent documentation developments:

- Updated bin/make-fancy-manual.sh to automate distribution on the
  web, including support for ACL2-Doc (by putting up text version of
  the combined manual).

- Updated *home-page* to mention new manuals/ page.


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1160 5d84a466-a78b-0930-a311-59b22171a541