docs: added utm_source for link from ds list page to docs page

public/app/features/plugins/partials/ds_list.html

@@ -49,7 +49,7 @@
 			buttonLink: '/datasources/new',
 			buttonTitle: 'Add data source',
 			proTip: 'You can also define data sources through configuration files.',
-			proTipLink: 'http://docs.grafana.org/administration/provisioning/#datasources',
+			proTipLink: 'http://docs.grafana.org/administration/provisioning/#datasources?utm_source=grafana_ds_list',
 			proTipLinkTitle: 'Learn more',
 			proTipTarget: '_blank'
 		}" />