Update README.md

README.md

@@ -60,7 +60,12 @@ One row of the dataset looks like this:
 
 ```python
 {
-
+  "fen": "2bq1rk1/pr3ppn/1p2p3/7P/2pP1B1P/2P5/PPQ2PB1/R3R1K1 w - -",
+  "line": "g2e4 f7f5 e4b7 c8b7 f2f3 b7f3 e1e6 d8h4 c2h2 h4g4",
+  "depth": 36,
+  "knodes": 206765,
+  "cp": 311,
+  "mate": None
 }
 ```
 
@@ -68,9 +73,9 @@ One row of the dataset looks like this:
 
 Every row of the dataset contains the following fields:
 
-- **`fen`**: `string`, 
-- **`line`**: `string`, 
-- **`depth`**: `string`, 
-- **`knodes`**: `int`, 
-- **`cp`**: `int`,
-- **`mate`**: `int`,
+- **`fen`**: `string`, the position FEN only contains pieces, active color, castling rights, and en passant square.
+- **`line`**: `string`, the principal variation, in UCI format.
+- **`depth`**: `string`, the depth reached by the engine.
+- **`knodes`**: `int`, the number of kilo-nodes searched by the engine.
+- **`cp`**: `int`, the position's centipawn evaluation. This is `None` if mate is certain.
+- **`mate`**: `int`, the position's mate evaluation. This is `None` if mate is not certain.