Update mixins.less

less/mixins.less

@@ -286,7 +286,7 @@
 
 // Reset filters for IE
 //
-// When you need to remove a gradient background, don't forget to use this to reset
+// When you need to remove a gradient background, do not forget to use this to reset
 // the IE filter for IE9 and below.
 .reset-filter() {
   filter: e(%("progid:DXImageTransform.Microsoft.gradient(enabled = false)"));