add doc

docs/en/sql-reference/functions/arithmetic-functions.md

@@ -89,6 +89,14 @@ divide(a, b)
 
 Alias: `a / b` (operator)
 
+## divideOrNull
+Like [divide](#divide) but returns NULL when the divisor is zero and return type is Nullable.
+**Syntax**
+
+```sql
+divideOrNull(a, b)
+```
+
 ## intDiv
 
 Performs an integer division of two values `a` by `b`, i.e. computes the quotient rounded down to the next smallest integer.
@@ -264,6 +272,15 @@ Result:
 └────────────────────────┘
 ```
 
+## moduloOrNull
+Like [modulo](#modulo) but returns NULL when the divisor is zero and return type is Nullable.
+
+**Syntax**
+
+```sql
+moduloOrNull(a, b)
+```
+
 ## negate
 
 Negates a value `a`. The result is always signed.