add missing semantics

Author: cometkim

text/0001-int.md

@@ -125,7 +125,8 @@ let exponentiate = (x, y) => {
 ### `remainder: (x: int, y: int) => int`
 
 1. If `y` equals `0`, raise `Divide_by_zero`.
-2. Let `number` be mathematically $x / y$.
+2. Let `number` be mathematically $x mod y$.
+3. Let `int32` be `fromNumber(number)`, return `int32`.
 
 ### `abs: (x: int) => int`