update intval doc with explicit binary numeral notation

[jawira]

In intval function, the base parameter allows to set the desired base to convert a string to int.

The base "0" works as "automatic base", the base will be detected:

echo intval('101', 0);   // 101
echo intval('0x101', 0); // 257
echo intval('0X101', 0); // 257
echo intval('0b101', 0); // 5
echo intval('0B101', 0); // 5
echo intval('0101', 0);  // 65

I updated the documentation to include binary 0b and 0B prefixes.

I would have liked to do the same for octal numeral notation, but 0o and 0O seems to not be implemented yet, only 0 works.

[TimWolla]

Thanks!