update doc

Author: sycai

bigframes/operations/output_schemas.py

@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""This file is specifically for parsing type strings for the output_schema parameter of AI functions.
-Do not use it from general SQL -> PyArrow type parsing as it does not handle all the types.
+"""This file is only for parsing type strings for the output_schema parameter of AI functions.
+Do not use it from general SQL -> PyArrow type parsing as it does not handle all the types. Plus
 """
 
 from typing import cast
@@ -25,7 +25,8 @@
 
 def parse_sql_fields(sql: str) -> tuple[pa.Field]:
     """
-    Parses a sequence of SQL struct fields into their PyArrow equivalents
+    Parses a sequence of SQL struct fields into their PyArrow equivalents. The returned fields
+    are sorted by name.
 
     Examples:
         "x INT64, y FLOAT64" => (pa.field("x", pa.int64()), pa.field("y", pa.float64()))