Make more explicit there are noise_types. (#6802)

* Make more explicit there are noise_types.

It helped me to convert https://docs.godotengine.org/en/stable/classes/class_opensimplexnoise.html to know of types in this example.

tutorials/math/random_number_generation.rst

@@ -445,6 +445,7 @@ terrain. Godot provides :ref:`class_fastnoiselite` for this, which supports
     func _ready():
         randomize()
         # Configure the FastNoiseLite instance.
+        _noise.noise_type = NoiseType.TYPE_SIMPLEX_SMOOTH
         _noise.seed = randi()
         _noise.fractal_octaves = 4
         _noise.frequency = 1.0 / 20.0
@@ -462,6 +463,7 @@ terrain. Godot provides :ref:`class_fastnoiselite` for this, which supports
     {
         GD.Randomize();
         // Configure the FastNoiseLite instance.
+        _noise.NoiseType = NoiseTypeEnum.SimplexSmooth;
         _noise.Seed = (int)GD.Randi();
         _noise.FractalOctaves = 4;
         _noise.Frequency = 1.0f / 20.0f;