Docs: fixes redirect from unified alerting (#51012)

* Docs: fixes redirect from unified alerting

* fixes mimir alerting rule redirect

* fixes mimir alerting rule redirect

* adds slash to redirect

docs/sources/alerting/alerting-rules/create-mimir-loki-managed-rule.md

@@ -3,6 +3,7 @@ aliases:
   - /docs/grafana/latest/alerting/alerting-rules/create-mimir-loki-managed-rule/
   - /docs/grafana/latest/alerting/unified-alerting/alerting-rules/create-cortex-loki-managed-recording-rule/
   - /docs/grafana/latest/alerting/unified-alerting/alerting-rules/create-mimir-loki-managed-recording-rule/
+  - /docs/grafana/latest/alerting/unified-alerting/alerting-rules/create-mimir-loki-managed-rule/
 description: Create Grafana Mimir or Loki managed alerting rule
 keywords:
   - grafana

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

@@ -2,6 +2,7 @@
 aliases:
   - /docs/grafana/latest/alerting/migrating-alerts/
   - /docs/grafana/latest/alerting/unified-alerting/
+  - /docs/grafana/latest/alerting/unified-alerting/difference-old-new/
 description: Upgrade Grafana alerts
 title: Upgrade to Grafana Alerting
 weight: 101