docs: css: Hide redundant 'Contents:' line in table of contents of RST docs

'docutils' add line saying "Contents:" on top of the table of contents.
We don't have that in other documents nor it's really necessary. Hide it
in the stylesheet as we can select it easily.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

docs/libvirt.css

@@ -597,3 +597,7 @@ th p, td p {
     margin-top: 2em;
     margin-bottom: 2em;
 }
+
+#contents p.topic-title {
+    display: none;
+}