ccl user manual

I=E2=80=99ve been doing some work on the CCL user manual.  The updated =
version may be found at https://ccl.clozure.com/docs/ccl.html.

I updated the HTML formatting by making a few tweaks to the CCLDoc HTML =
renderer, and I also borrowed a bunch of CSS from =
https://ziglang.org/documentation/master/.

The sources for the manual are part of the CCL repository.  The user =
manual is in ccl:doc;manual; and I just added a basic Makefile so that =
it=E2=80=99s a little easier to format it.

To run the Makefile, edit it so that the CCLDOC_ROOT variable points to =
your local checkout of CCLDoc.

The stylesheet used by the manual is at ccl:doc;manual;style.css, and =
I=E2=80=99d happily take patches or pull requests from those who are =
better at web stuff than I am.  Of course, I=E2=80=99ll also happily =
take pull requests for other aspects of the manual as well.

It would be cool to have a GitHub workflow that would notice when =
anything in ccl:doc;manual; got updated and automatically build and =
update the version of the manual that=E2=80=99s at =
https://ccl.clozure.com/docs/ccl.html.