docs(reliability.md): add tutorial on disabling fallbacks per key

docs/my-website/docs/proxy/reliability.md

@@ -748,4 +748,19 @@ curl -L -X POST 'http://0.0.0.0:4000/v1/chat/completions' \
     "max_tokens": 300,
     "mock_testing_fallbacks": true
 }'
+```
+
+### Disable Fallbacks per key
+
+You can disable fallbacks per key by setting `disable_fallbacks: true` in your key metadata.
+
+```bash
+curl -L -X POST 'http://0.0.0.0:4000/key/generate' \
+-H 'Authorization: Bearer sk-1234' \
+-H 'Content-Type: application/json' \
+-d '{
+    "metadata": {
+        "disable_fallbacks": true
+    }
+}'
 ```