Added comments

build/less/core.less

@@ -45,6 +45,7 @@ body {
 .content-wrapper, 
 .right-side,
 .main-footer {    
+  //Using disposable variable to join statements with a comma
   @transition-rule: @transition-speed @transition-fn,
                     margin-left @transition-speed @transition-fn;
   .transition-transform(@transition-rule);

build/less/sidebar.less

@@ -14,6 +14,7 @@
   min-height: 100%;
   width: @sidebar-width;
   z-index: 810;
+  //Using disposable variable to join statements with a comma
   @transition-rule: @transition-speed @transition-fn, 
                       width @transition-speed @transition-fn;
   .transition-transform(@transition-rule);