small doc fix [CI SKIP]

doc/ci/yaml/README.md

@@ -1498,7 +1498,7 @@ Possible values for `when` are:
 - `always`: Retry on any failure (default).
 - `unknown_failure`: Retry when the failure reason is unknown.
 - `script_failure`: Retry when the script failed.
-- `api_failure`: Retry on api failure.
+- `api_failure`: Retry on API failure.
 - `stuck_or_timeout_failure`: Retry when the job got stuck or timed out.
 - `runner_system_failure`: Retry if there was a runner system failure (e.g. setting up the job failed).
 - `missing_dependency_failure`: Retry if a dependency was missing.