Update README.md

README.md

@@ -54,10 +54,8 @@ original monthly archives are available from the
 [BTS PREZIP archive](https://transtats.bts.gov/PREZIP/). This dataset is not an
 official BTS publication.
 
-The market deltas input is the original user-supplied Parquet export used for
-the benchmark. Its Parquet metadata identifies ClickHouse 26.4.1 as the
-writer. It contains event timestamps, worker and venue identifiers, market and
-instrument keys, outcome and book-side labels, price, size, and update kind.
+The market deltas contains event timestamps, worker and venue identifiers, market and
+instrument keys, outcome and book-side labels, price, size, and update kind from prediction market historical data.
 No broader source attribution or license was embedded in the file, so users
 must establish that their intended use is permitted.