Note the Hive partition columns

README.md

@@ -67,6 +67,9 @@ table = ds.dataset(path, format="parquet", partitioning="hive")
 | `longitude` | double | stop position |
 | `door_lift_flags_possibly` | string | vehicle flag field; its low bit separates the two APC-equipped subfleets |
 
+Readers that understand Hive partitioning also surface `year` and `month` as
+columns, recovered from the directory names rather than stored in the files.
+
 ## Working with it
 
 These are **raw counts, not ridership estimates.** Two corrections matter