Merge pull request #17448 from lukeb-uk/navbar_toggleable_md

Add .navbar-toggleable-md class

scss/_navbar.scss

@@ -129,6 +129,11 @@
       display: block !important;
     }
   }
+  &-md {
+    @include media-breakpoint-up(lg) {
+      display: block !important;
+    }
+  }
 }