docs: Minor readme updates

README.md

@@ -18,6 +18,8 @@ For each symbol, 2 files are provided:
 - `ticks.parquet` contains the ticker data
 - `gaps.parquet` contains the reported time gaps
 
+A merge of all datasets is also provided in `all_ticks.parquet` and `all_gaps.parquet `. The datasets are concatenated and a symbol column is added.
+
 ## Ticks
 
 The `ticks.parquet` files have the following schema:
@@ -41,10 +43,10 @@ The `gaps.parquet` files have the following schema:
 {
     # The gap duration
     'length': pl.UInt64,
-    # The untransformed gap timestap start reported in the .txt file
-    'start': pl.UInt64,
-    # The untransformed gap timestap end reported in the .txt file
-    'end': pl.UInt64,
+    # The timestamp of the gap start converted to UTC.
+    'start': pl.Datetime,
+    # The timestamp of the gap end converted to UTC.
+    'end': pl.Datetime,
 }
 ```