not just 404

Co-authored-by: Eric Huss <eric@huss.org>

Author: Eh2406

src/doc/src/reference/registries.md

@@ -320,7 +320,9 @@ visit the registry's website to obtain a token, and Cargo can store the token
 using the [`cargo login`] command, or by passing the token on the
 command-line.
 
-Responses should use the 200 or 404 response code as appropriate. Failure
+Responses use the 200 response code for success.
+Errors should use an appropriate response code, such as 404.
+Failure
 responses should have a JSON object with the following structure:
 
 ```javascript