fixes #22111

- add .col-*-auto to the extend in our grid framework mixins so it gets padding
- this means we can avoid the col-12 classes in our docs for the responsive variants

scss/mixins/_grid-framework.scss

@@ -22,7 +22,8 @@
         @extend %grid-column;
       }
     }
-    .col#{$infix} {
+    .col#{$infix},
+    .col#{$infix}-auto {
       @extend %grid-column;
     }