Specify the floating point accuracy of the round() function (#951)

* Specify the floating point accuracy of the round() function

* Update docs-2.0/3.ngql-guide/6.functions-and-expressions/1.math.md

Co-authored-by: randomJoe211 <[email protected]>

Co-authored-by: randomJoe211 <[email protected]>

docs-2.0/3.ngql-guide/6.functions-and-expressions/1.math.md

@@ -9,7 +9,7 @@ Function| Description |
 double abs(double x) | Returns the absolute value of the argument. |
 double floor(double x) | Returns the largest integer value smaller than or equal to the argument. (Rounds down) |
 double ceil(double x) | Returns the smallest integer greater than or equal to the argument. (Rounds up) |
-double round(double x) | Returns the integer value nearest to the argument. Returns a number farther away from 0 if the argument is in the middle. |
+double round(double x, int y) | Returns the rounded value of x. y specifies the rounding index (position). If y is greater than 0, round at the yth position to the right of the decimal point. If y is less than 0, round at the yth position to the left of the decimal point. <br>Pay attention to the floating-point precision when using this function. |
 double sqrt(double x) | Returns the square root of the argument. |
 double cbrt(double x) | Returns the cubic root of the argument. |
 double hypot(double x, double y) | Returns the hypotenuse of a right-angled triangle. |