fix(AIP-194): fix link to client libs (#1179)

Author: noahdietz

aip/general/0194.md

@@ -29,7 +29,8 @@ 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.
+**Note:** For client side retry behavior in the client libraries: see
+[AIP-4221](./client-libraries/4221.md).
 
 ### Retryable codes