Merge pull request #15852 from grafana/15851-update-error-message

Update error message and replace npm with yarn

public/views/index-template.html

@@ -179,8 +179,7 @@
       <p>
         1. This could be caused by your reverse proxy settings.<br /><br />
         2. If you host grafana under subpath make sure your grafana.ini root_url setting includes subpath<br /> <br />
-        3. If you have a local dev build make sure you build frontend using: npm run dev, npm run watch, or npm run
-        build<br /> <br />
+        3. If you have a local dev build make sure you build frontend using: yarn start, yarn start:hot, or yarn build<br /> <br />
         4. Sometimes restarting grafana-server can help<br />
       </p>
     </div>