chore(AIP-194): fix broken AIP-4221 link (#1361)

Author: leahecole

aip/general/0194.md

@@ -30,7 +30,7 @@ would cause unintended state changes.
 **Note:** This AIP does not cover client streaming or bi-directional streaming.
 
 **Note:** For client side retry behavior in the client libraries: see
-[AIP-4221](./client-libraries/4221.md).
+[AIP-4221][].
 
 ### Retryable codes