added better comments

wagtail/wagtailadmin/static/wagtailadmin/css/variables.less

@@ -1,17 +1,20 @@
+/* paths */
 @static-root: "/static/wagtailadmin/images/";
 @css-root: "/static/wagtailadmin/css/";
 
+/* grid settings */
 @grid-columns: 12; 
 @grid-gutter-width: 3%;
 @grid-max-width: 1200px;
 @grid-content-indent:0.7;
 
+/* screen breakpoints */
 @breakpoint-mobile:50em; /* 800px */
 @breakpoint-desktop-small:56.25em; /* 900px */
 @breakpoint-desktop-large:75em; /* 1200px */
 @breakpoint-desktop-larger:100em; /* 1600px */
 
-// generic colours
+/* colours */
 @color-teal: #43b1b0;
 @color-teal-darker: darken(@color-teal, 10%);
 @color-teal-dark: #246060;
@@ -19,7 +22,7 @@
 @color-orange:#e9b04d;
 @color-green: #00FF00;
 
-/* greys, darker to lighter */
+/* darker to lighter */
 @color-grey-1: #333333;
 @color-grey-1-1: #404040;
 @color-grey-2: #666666;
@@ -45,7 +48,6 @@
 @color-text-base: @color-grey-2;
 @color-text-input: @color-grey-1;
 
-
+/* misc sizing */
 @thumbnail-width:130px;
-
 @menu-width: 150px;