Docs: fixes data source links (#52196)

* Docs: fixes data source links

* fixes unified alerting redirect

docs/sources/alerting/fundamentals/data-source-alerting.md

@@ -19,7 +19,7 @@ These are the data sources that are compatible with and supported by Grafana Ale
 - [AWS CloudWatch]({{< relref "../../datasources/aws-cloudwatch/" >}})
 - [Azure Monitor]({{< relref "../../datasources/azuremonitor/" >}})
 - [Elasticsearch]({{< relref "../../datasources/elasticsearch/" >}})
-- [Google Cloud Monitoring]({{< relref "../../google-cloud-monitoring/" >}})
+- [Google Cloud Monitoring]({{< relref "../../datasources/google-cloud-monitoring/" >}})
 - [Graphite]({{< relref "../../datasources/graphite/" >}})
 - [InfluxDB]({{< relref "influxdb/" >}})
 - [Loki]({{< relref "../../datasources/loki/" >}})

docs/sources/alerting/migrating-alerts/_index.md

@@ -3,6 +3,7 @@ aliases:
   - /docs/grafana/latest/alerting/migrating-alerts/
   - /docs/grafana/latest/alerting/unified-alerting/
   - /docs/grafana/latest/alerting/unified-alerting/difference-old-new/
+  - /docs/grafana/latest/alerting/difference-old-new/
 description: Upgrade Grafana alerts
 title: Upgrade to Grafana Alerting
 weight: 101