Correct the default value of "algorithm" in README

[Kiyamou]

The default value of algorithm is 0, not 1.

VapourSynth-Bilateral/source/Bilateral.cpp

Lines 238 to 252 in 5c246c0

	m = vsapi->propNumElements(in, "algorithm");
	for (i = 0; i < 3; i++)
	{
	if (i < m)
	{
	d.algorithm[i] = int64ToIntS(vsapi->propGetInt(in, "algorithm", i, nullptr));
	}
	else if (i == 0)
	{
	d.algorithm[i] = 0;
	}
	else
	{
	d.algorithm[i] = d.algorithm[i - 1];
	}

The rest of README about algorithm ‘s default value is correct, only this one is wrong.