chore: link to details of iOS behaviour

src/components/controls/variables.scss

@@ -1,3 +1,4 @@
 $border-width: 1px;
 // Safari on iOS zoom page if input font-size is smaller than 16px
+// https://css-tricks.com/16px-or-larger-text-prevents-ios-form-zoom/
 $mobile-safari-font-size: 16px;