Update README.md

README.md

@@ -4677,6 +4677,12 @@ Each record in the dataset has the following structure:
 - `Termination`: string, reason for game termination.
 - `Transcript`: string, sequence of moves in UCI format. Note: Promotions are capitalized.
 
+
+### Python Chess Gotchas
+For those new to the datasets here's a few things to watch out for:
+- The python Chess library uses lowercase letters to indicate pawn promotion, but this dataset uses upper-case letters instead (as a natural consequence of using `pgn-extract`, this also disambiguates bishop promotions 'b' from the b-file (column)). You may want to use `str.lower()` whenever processing transcripts with the Chess library.
+- Empty transcripts are using '0-1' by `pgn-extract`. (example: lichess.org/AvQ6x3da)
+
 ### Human versus Bot Players
 
 The source data comes from games played on Lichess.org, an online platform where users from around the world play chess.