docs: add styling for <tt> element

Although <tt> is deprecated in HTML5, the rst2html command will still
emit it, in preference to <code> tags, so we must style it too.
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

docs/generic.css

@@ -72,11 +72,11 @@ h6 {
   font-size: 0.8em;
 }
 
-code, pre {
+code, pre, tt {
   font-family: LibvirtOverpassMono;
 }
 
-dd code, p code {
+dd code, p code, tt {
   background-color: #eeeeee;
 }