fix typo in file-search.md

Author: Aarons9090

articles/ai-services/agents/how-to/tools/file-search.md

@@ -87,7 +87,7 @@ The maximum file size is 512 MB. Each file should contain no more than 5,000,000
 
 We highly recommend that you ensure all files in a vector_store are fully processed before you create a run. This ensures that all the data in your vector store is searchable. You can check for vector store readiness by using the polling helpers in the SDKs, or by manually polling the vector store object to ensure the status is completed.
 
-As a fallback, there's a 60-second maximum wait in the run object when the thread's vector store contains files that are still being processed. This is to ensure that any files your users upload in a thread a fully searchable before the run proceeds. This fallback wait does not apply to the agent's vector store.
+As a fallback, there's a 60-second maximum wait in the run object when the thread's vector store contains files that are still being processed. This is to ensure that any files your users upload in a thread are fully searchable before the run proceeds. This fallback wait does not apply to the agent's vector store.
 
 ## Add file search to an agent using the Azure AI Foundry portal