docs: reduce excessive spacing in ToC for RST files

The table of contents in the RST based files uses <p> tags inside the
<li>, which results in 1em's worth of spacing above & below each
entry. This results in way too much whitespace in the ToC.
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

docs/libvirt.css

@@ -579,3 +579,7 @@ ul.news-section-content li dl dd {
     font-family: monospace;
     background: #eeeeee;
 }
+
+.contents li p {
+    margin: 2px;
+}