Add C# example for the AudioStreamGenerator code snippet

doc/classes/AudioStreamGenerator.xml

@@ -6,7 +6,8 @@
 	<description>
 		[AudioStreamGenerator] is a type of audio stream that does not play back sounds on its own; instead, it expects a script to generate audio data for it. See also [AudioStreamGeneratorPlayback].
 		Here's a sample on how to use it to generate a sine wave:
-		[codeblock]
+		[codeblocks]
+		[gdscript]
 		var playback # Will hold the AudioStreamGeneratorPlayback.
 		@onready var sample_hz = $AudioStreamPlayer.stream.mix_rate
 		var pulse_hz = 440.0 # The frequency of the sound wave.
@@ -24,7 +25,39 @@
 		    for i in range(frames_available):
 		        playback.push_frame(Vector2.ONE * sin(phase * TAU))
 		        phase = fmod(phase + increment, 1.0)
-		[/codeblock]
+		[/gdscript]
+		[csharp]
+		[Export] public AudioStreamPlayer Player { get; set; }
+
+		private AudioStreamGeneratorPlayback _playback; // Will hold the AudioStreamGeneratorPlayback.
+		private float _sampleHz;
+		private float _pulseHz = 440.0f; // The frequency of the sound wave.
+
+		public override void _Ready()
+		{
+		    if (Player.Stream is AudioStreamGenerator generator) // Type as a generator to access MixRate.
+		    {
+		        _sampleHz = generator.MixRate;
+		        Player.Play();
+		        _playback = (AudioStreamGeneratorPlayback)Player.GetStreamPlayback();
+		        FillBuffer();
+		    }
+		}
+
+		public void FillBuffer()
+		{
+		    double phase = 0.0;
+		    float increment = _pulseHz / _sampleHz;
+		    int framesAvailable = _playback.GetFramesAvailable();
+
+		    for (int i = 0; i &lt; framesAvailable; i++)
+		    {
+		        _playback.PushFrame(Vector2.One * (float)Mathf.Sin(phase * Mathf.Tau));
+		        phase = Mathf.PosMod(phase + increment, 1.0);
+		    }
+		}
+		[/csharp]
+		[/codeblocks]
 		In the example above, the "AudioStreamPlayer" node must use an [AudioStreamGenerator] as its stream. The [code]fill_buffer[/code] function provides audio data for approximating a sine wave.
 		See also [AudioEffectSpectrumAnalyzer] for performing real-time audio spectrum analysis.
 		[b]Note:[/b] Due to performance constraints, this class is best used from C# or from a compiled language via GDExtension. If you still want to use this class from GDScript, consider using a lower [member mix_rate] such as 11,025 Hz or 22,050 Hz.