user-manual: install user manual stylesheet with other web documents

Install the stylesheet needed for the user manual.  This should solve
the problem of, e.g.,

	http://www.kernel.org/pub/software/scm/git/docs/user-manual.html

lacking a lot of formatting.

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>

Documentation/install-webdoc.sh

@@ -2,7 +2,7 @@
 
 T="$1"
 
-for h in *.html *.txt howto/*.txt howto/*.html RelNotes-*.txt
+for h in *.html *.txt howto/*.txt howto/*.html RelNotes-*.txt *.css
 do
 	if test -f "$T/$h" &&
 	   diff -u -I'Last updated [0-9][0-9]-[A-Z][a-z][a-z]-' "$T/$h" "$h"