Thin out the border around link-sharing onboarding popover arrow

services/web/public/stylesheets/app/editor/feature-onboarding.less

@@ -170,7 +170,7 @@ a.feat-onboard-dismiss {
 	&.bottom::before {
 		border-top-width: 0;
 		border-bottom-color: rgba(0, 0, 0, .3);
-		top: -11px;
+		top: -10px;
 		right: 38px;
 	}