docs: Update README.md and godoc for Boolean-to-Number coercion

- Added documentation section to README.md explaining automatic coercion
- Included usage examples: '5 3 == 1 +', '0 false +', 'true 2 *', '9 3 > 4 5 < +'
- Updated Value type godoc to explain coercion behavior (true→1, false→0)
- toNumber() function already had good documentation

The coercion allows boolean results to be used directly in arithmetic operations,
enabling expressions like '5 3 == 1 +' where '5 3 ==' produces false=0, then '0 + 1' produces 1.

1 files changed, 24 insertions, 0 deletions

diff --git a/README.md b/README.md
index 5c8fcba..9f4de3e 100644
--- a/README.md
+++ b/README.md
@@ -179,6 +179,30 @@ To show the current stack without modifying it:
 45
 ```
 
+## Boolean-to-Number Coercion
+
+Boolean values are automatically coerced to numbers when used in arithmetic operations:
+- `true` is treated as `1`
+- `false` is treated as `0`
+
+This enables mixed boolean-numeric expressions:
+
+```bash
+gt 5 3 == 1 +      # 5 == 3 is false (0), 0 + 1 = 1
+# → 1
+
+gt 0 false +       # false is 0, 0 + 0 = 0
+# → 0
+
+gt true 2 *        # true is 1, 1 * 2 = 2
+# → 2
+
+gt 9 3 > 4 5 < +   # 9 > 3 is true (1), 4 < 5 is true (1), 1 + 1 = 2
+# → 2
+```
+
+Note: The boolean result is shown as `true`/`false` when printed, but when used as an operand it behaves as the corresponding numeric value.
+
 ## Hyper Operators
 
 Hyper operators work on all values on the stack simultaneously: