docs: clarify that the presence of XyzJob.errors doesn't necessarily mean that the job has not completed or was unsuccessful (#2278)

Internal issue b/440349994

Author: tswast

google/cloud/bigquery/job/base.py

@@ -693,7 +693,12 @@ def transaction_info(self) -> Optional[TransactionInfo]:
 
     @property
     def error_result(self):
-        """Error information about the job as a whole.
+        """Output only. Final error result of the job.
+
+        If present, indicates that the job has completed and was unsuccessful.
+
+        See:
+        https://cloud.google.com/bigquery/docs/reference/rest/v2/Job#JobStatus.FIELDS.error_result
 
         Returns:
             Optional[Mapping]: the error information (None until set from the server).
@@ -704,7 +709,13 @@ def error_result(self):
 
     @property
     def errors(self):
-        """Information about individual errors generated by the job.
+        """Output only. The first errors encountered during the running of the job.
+
+        The final message includes the number of errors that caused the process to stop.
+        Errors here do not necessarily mean that the job has not completed or was unsuccessful.
+
+        See:
+        https://cloud.google.com/bigquery/docs/reference/rest/v2/Job#JobStatus.FIELDS.errors
 
         Returns:
             Optional[List[Mapping]]:
@@ -716,7 +727,12 @@ def errors(self):
 
     @property
     def state(self):
-        """Status of the job.
+        """Output only. Running state of the job.
+
+        Valid states include 'PENDING', 'RUNNING', and 'DONE'.
+
+        See:
+        https://cloud.google.com/bigquery/docs/reference/rest/v2/Job#JobStatus.FIELDS.state
 
         Returns:
             Optional[str]: