docs: add Azure env vars to AGENTS.md

Author: DeveshParagiri

AGENTS.md

@@ -136,6 +136,8 @@ export OPENAI_API_KEY=sk-...
 export ANTHROPIC_API_KEY=sk-ant-...
 export OPENROUTER_API_KEY=sk-or-...
 export DEEPSEEK_API_KEY=sk-...
+export AZURE_API_KEY=...
+export AZURE_ENDPOINT=https://<resource>.services.ai.azure.com/
 ```
 
 ## Global Flags