Generate a basic documentation website with the mkdocs toolkit.

No content yet other than man pages.  To make the man pages render
nicely in mkdocs, I removed the static %-headers and put the code for
them into default.md.tmp.do instead.  That way, the raw input redo-*.md
files will look right in mkdocs.

Documentation/default.md.tmp.do

@@ -1,3 +1,7 @@
 redo-ifchange ../version/vars $2.md
 . ../version/vars
-sed -e "s/%VERSION%/$TAG/" -e "s/%DATE%/$DATE/" $2.md
+cat - $2.md <<-EOF
+	% $2(1) Redo $TAG
+	% Avery Pennarun <apenwarr@gmail.com>
+	% $DATE
+EOF