Restore index link states to the way they are in current guide

Current stable guides show the "Guides Index" links without underline,
just showing it when it's hovered. This restores the same functionality
for edge guides.

Also remove annoying pointer cursor while accessing guides index,
restoring previously functionality: now the pointer cursor only appears
when hovering a link.

Closes #8107 [ci skip]

guides/assets/stylesheets/main.css

@@ -313,7 +313,6 @@ a, a:link, a:visited {
   background: #980905;
   position: relative;
   color: white;
-  cursor: pointer;
 }
 
 .guides-index .guides-index-item {
@@ -408,7 +407,8 @@ a, a:link, a:visited {
   padding: 0;
 }
 #guides dt {padding:0; margin: 0.5em 0 0;}
-#guides a {color: #FFF; background: none !important;}
+#guides a {color: #FFF; background: none !important; text-decoration: none;}
+#guides a:hover {text-decoration: underline;}
 #guides .L, #guides .R {float: left; width: 50%; margin: 0; padding: 0;}
 #guides .R {float: right;}
 #guides hr {