Adjust margin of input-group.

src/client/js/components/SlackNotification.jsx

@@ -54,7 +54,7 @@ class SlackNotification extends React.Component {
             </div>
           </label>
           <input
-            className="grw-form-control-slack-notification form-control align-top"
+            className="grw-form-control-slack-notification form-control align-top ml-n2"
             type="text"
             value={this.props.slackChannels}
             placeholder="Input channels"