Document CodeQL `float` `floor()` and `ceil()` behavior for values outside of `int` range

The documentation for the CodeQL predicates `float.floor()` and `float.ceil()` says:
> Returns the largest integer that is not greater than the receiver

> Returns the smallest integer greater than or equal to the receiver

For both the documentation is incorrect for results outside the `int` value range. The actual behavior of these predicates is that they use the minimum / maximum `int` value if the value exceeds the `int` value range, as seen with this query:
```codeql
from float f
where f = [2200000000.0, -2200000000.0]
select f, f.floor() as floor, f.ceil() as ceil
```

The results are:
| f | floor | ceil |
| -- | -- | -- |
| -2200000000 | -2147483648 | -2147483648
| 2200000000 | 2147483647 | 2147483647

(Tested with CodeQL CLI 2.13.1)

It would be good if the documentation for `floor()` and `ceil()` is adjusted to explicitly mention this.

This might also have to be adjusted in the [QL language specification](https://codeql.github.com/docs/ql-language-reference/ql-language-specification/#built-ins-for-float).