docs: Clean-up font definitions

Some of those were duplicate, so remove those.  In order to better see
such things in the future, sort them so they are "regular, italic,
bold, bold-italic, light, light-italic".
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

docs/fonts/stylesheet.css

-@font-face {
-	font-family: 'LibvirtOverpass';
-	src: url('hinted-Overpass-Italic.woff') format('woff');
-	font-weight: normal;
-	font-style: italic;
-}
-
-@font-face {
-	font-family: 'LibvirtOverpass';
-	src: url('hinted-Overpass-Bold.woff') format('woff');
-	font-weight: bold;
-	font-style: normal;
-}
-
 @font-face {
 	font-family: 'LibvirtOverpass';
 	src: url('hinted-Overpass-Reg.woff') format('woff');
@@ -21,9 +7,9 @@
 
 @font-face {
 	font-family: 'LibvirtOverpass';
-	src: url('hinted-Overpass-Reg.woff') format('woff');
+	src: url('hinted-Overpass-Italic.woff') format('woff');
 	font-weight: normal;
-	font-style: normal;
+	font-style: italic;
 }
 
 @font-face {