Added lookarounds and numeric ranges to documentation

regex/doc.go

@@ -84,6 +84,17 @@ Assertions:
 	\b				Match at a word boundary (a word character followed by a non-word character, or vice-versa)
 	\B				Match at a non-word boundary (a word character followed by a word character, or vice-versa)
 
+Lookarounds:
+
+	x(?=y)			Positive lookahead - Match x if followed by y
+	x(?!y)			Negative lookahead - Match x if NOT followed by y
+	(?<=x)y			Positive lookbehind - Match y if preceded by x
+	(?<!x)y			Negative lookbehind - Match y if NOT preceded by x
+
+Numeric ranges:
+
+	<x-y>			Match any number from x to y (inclusive) (x and y must be positive numbers)
+
 # Flags
 
 Flags are used to change the behavior of the engine. None of them are enabled by default. They are passed as variadic arguments to [Compile].