Update autorest.md file (Azure#18729)

Author: ShivangiReja

sdk/anomalydetector/Azure.AI.AnomalyDetector/src/autorest.md

@@ -3,8 +3,8 @@
 Run `dotnet build /t:GenerateCode` to generate code.
 
 ``` yaml
-input-file:
-    -  https://github.com/Azure/azure-rest-api-specs/blob/f3ed9637897d9f095a8ec28ed82f59ec85fff954/specification/cognitiveservices/data-plane/AnomalyDetector/preview/v1.0/AnomalyDetector.json
+require:
+    -  https://github.com/Azure/azure-rest-api-specs/blob/f3ed9637897d9f095a8ec28ed82f59ec85fff954/specification/cognitiveservices/data-plane/AnomalyDetector/readme.md
 namespace: Azure.AI.AnomalyDetector
 public-clients: true
 ```