Update README.md

Author: miroiu

README.md

@@ -2,8 +2,8 @@
 Calculates the value of a math expression from a string returning a decimal.
 Supports variables and user defined operators.
 
+### Creating and using a calculator
 ```csharp
-// Evaluating a simple expression
 Calculator myCalculator = new Calculator();
 decimal result = myCalculator.Evaluate("1 * (2 - 3) ^ 2"); // 1
 
@@ -16,8 +16,8 @@ myCalculator.AddOperator("max", (a, b) => a > b ? a : b, Precedence.Power);
 decimal result = myCalculator.Evaluate("2 * 3 max 4"); // 8
 ```
 
-```csharp 
-// Using a variables collection
+### Creating and using variables
+```csharp
 Replacements variables = new Replacements
 {
 	["a"] = 5,
@@ -32,8 +32,9 @@ myCalculator.Replace("b", 1);
 decimal result = calculator.Evaluate("{a} + 2 * {b} + {PI}"); // 7.1415926535897931
 ```
 
+### Using the static api: SMath
 ```csharp
-// Using the static class SMath
+// Same API as a calculator instance except the Evaluate method
 decimal result = SMath.Evaluate("1 + 1"); // 2
 decimal result = SMath.Evaluate("1 + {myVar}", new Replacements { ["myVar"] = 1 }); // 2
 ```