Add note for responsive modal styles

ui/app/components/modal.js

@@ -32,6 +32,7 @@ Modal.prototype.render = function () {
 
   return h(FadeModal,
     {
+      className: 'modal',
       keyboard: false,
       onHide: () => {this.onHide()},
       ref: (ref) => {

ui/app/css/itcss/components/modal.scss

@@ -0,0 +1,5 @@
+.modal {
+  // first child - component
+  // second child - background
+  //  boron should provide them, but we need breakpoints
+}