Adjust Carbon Ads margin on -xs

The .container that immediately surrounds .carbonad has a padding of 15px, not 30px.

Fixes #16552.

docs/assets/css/src/docs.css

@@ -356,7 +356,7 @@ h4 code {
   width: auto !important;
   height: auto !important;
   padding: 20px !important;
-  margin: 30px -30px -31px !important;
+  margin: 30px -15px -31px !important;
   overflow: hidden; /* clearfix */
   font-size: 13px !important;
   line-height: 16px !important;