[v10.0.x] Docs: fixes broken alias redirect (#71737)

Docs: fixes broken alias redirect (#71730)

(cherry picked from commit 7738a9846c)

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>

docs/sources/alerting/alerting-rules/_index.md

@@ -4,6 +4,7 @@ aliases:
   - old-alerting/create-alerts/
   - rules/
   - unified-alerting/alerting-rules/
+  - ./create-alerts/
 description: Configure alerting
 title: Configure Alerting
 weight: 130