move around some comments in buttons.less, update labels to use correct variables, add snippet to docs about IE9

lib/buttons.less

@@ -1,6 +1,10 @@
 // BUTTON STYLES
 // -------------
 
+
+// Colors
+// ------
+
 .btn {
   // Set text color
   &.primary,
@@ -31,6 +35,9 @@
   }
 }
 
+
+// Mixin for generating button backgrounds
+// ---------------------------------------
 .buttonBackground(@startColor, @endColor) {
   // gradientBar will set the background to a pleasing blend of these, to support IE<=9
   .gradientBar(@startColor, @endColor);
@@ -40,18 +47,22 @@
     background-color: @endColor;
   }
 
+  // called out separately because IE8 would ignore otherwise
   &[disabled] {
     background-color: @endColor;
   }
 
+  // IE 7 + 8 can't handle box-shadow to show active, so we darken a bit ourselves
   &:active,
   &.active {
-    // IE 7 + 8 can't handle box-shadow to show active, so we darken a bit ourselves
     background-color: darken(@endColor, 10%) e("\9");
   }
 }
 
-// Base .btn styles
+
+// Base styles
+// -----------
+
 .btn {
   // Button Base
   display: inline-block;

lib/labels.less

@@ -9,8 +9,8 @@
   text-transform: uppercase;
   background-color: @grayLight;
   .border-radius(3px);
-  &.important { background-color: #c43c35; }
+  &.important { background-color: @errorText; }
   &.warning   { background-color: @orange; }
-  &.success   { background-color: @green; }
-  &.notice    { background-color: lighten(@blue, 25%); }
+  &.success   { background-color: @successText; }
+  &.info      { background-color: @infoText; }
 }