docs: Add ChainSum usage example to README

README.md

@@ -4,6 +4,50 @@ We are building a python library of procedural dataset generators and algorithmi
 
 The goal is to generate virtually infinite data with adjustable complexity.
 
+## Quick Start
+
+```python
+from reasoning_gym.arithmetic import ChainSum, ChainSumConfig
+
+# Configure a simple arithmetic task generator
+config = ChainSumConfig(
+    min_terms=2,          # At least 2 numbers per expression
+    max_terms=4,          # At most 4 numbers per expression
+    min_digits=1,         # Single digit numbers
+    max_digits=2,         # Up to 2-digit numbers
+    allow_negation=False, # Only positive numbers
+    size=5,              # Generate 5 examples
+    seed=42              # For reproducibility
+)
+
+# Create the dataset
+dataset = ChainSum(config)
+
+# Generate some examples
+for i in range(len(dataset)):
+    item = dataset[i]
+    print(f"Question: {item['question']}")
+    print(f"Answer: {item['answer']}\n")
+```
+
+Example output:
+```
+Question: 7 + 42 - 15 =
+Answer: 34
+
+Question: 91 - 8 =
+Answer: 83
+
+Question: 4 + 67 - 12 =
+Answer: 59
+
+Question: 28 + 35 =
+Answer: 63
+
+Question: 51 - 24 + 7 =
+Answer: 34
+```
+
 
 ### Generator / Environment Ideas