Remove margin-bottom on .bd-example (#25048)

Author: mdo

assets/scss/_component-examples.scss

@@ -117,15 +117,14 @@
 .bd-example {
   position: relative;
   padding: 1rem;
-  margin: 1rem (-$grid-gutter-width / 2);
+  margin: 1rem (-$grid-gutter-width / 2) 0;
   border: solid #f7f7f9;
   border-width: .2rem 0 0;
   @include clearfix();
 
   @include media-breakpoint-up(sm) {
     padding: 1.5rem;
     margin-right: 0;
-    margin-bottom: 0;
     margin-left: 0;
     border-width: .2rem;
   }