* doc/card-games.texi: fill in Introduction, Installation, The Game Menu,
Playing, and Customization with real text and @findex/@vindex indexing;
add sub-sections for installation and customization.
* doc/card-games.texi: new manual skeleton -- header, CC-BY-4.0 copying,
dir entry, title page, Top menu, stub chapters for every section, and the
index. Builds cleanly with makeinfo.
* Makefile (info, html, pdf, docclean): build the manual; add the source
to the package tarball.
* .gitignore: ignore the generated manual outputs.
