update link to Slack token generation.

frontend/src/admin/settings/components/SettingsSlackForm.jsx

@@ -205,13 +205,14 @@ export default class SettingsSlackForm extends Component {
                     <h3 className="text-grey-1">Answers sent right to your Slack #channels</h3>
 
                     <div className="pt3">
-                        <a href="https://api.slack.com/web#authentication" target="_blank" className="Button Button--primary" style={{padding:0}}>
+                        <a href="https://api.slack.com/docs/oauth-test-tokens" target="_blank" className="Button Button--primary" style={{padding:0}}>
                             <div className="float-left py2 pl2">Get an API token from Slack</div>
                             <Icon className="float-right p2 text-white cursor-pointer" style={{opacity:0.6}} name="external" width={18} height={18}/>
                         </a>
                     </div>
                     <div className="py2">
                         Once you're there, click <strong>"Create token"</strong> next to the team that you want to integrate with Metabase, then copy and paste the token into the field below.
+                        Slack test tokens work fine with Metabase.
                     </div>
                 </div>
                 <ul>