Group inverted navbar vars under a subheading

[skip sauce]
[skip validator]

less/variables.less

@@ -388,7 +388,7 @@
 @navbar-default-toggle-border-color:       #ddd;
 
 
-// Inverted navbar
+//=== Inverted navbar
 // Reset inverted navbar basics
 @navbar-inverse-color:                      lighten(@gray-light, 15%);
 @navbar-inverse-bg:                         #222;