message: Shader doc fixes per comments
diff: @@ -128,11 +128,11 @@ impl<'a> ShaderBuilder<'a> {
  }
  }
  -/// A custom fragment shader that can be used to render with shader effects.
  +/// A custom shader that can be used to render with shader effects.
  ///
  -/// The program may have a user specified vertex shader, fragment shader, both,
  -/// or neither. The fragment shader entry point must be named fs_main. The
  -/// vertex shader entry point must be named vs_main. The vertex shader must
  +/// The shader may have a user specified vertex module, fragment module, both,
  +/// or neither. The fragment module entry point must be named fs_main. The
  +/// vertex module entry point must be named vs_main. The vertex module must
  /// have an output of type
  /// ```wgsl
  /// struct VertexOutput {
  @@ -141,7 +141,7 @@ impl<'a> ShaderBuilder<'a> {
  /// @location(1) color: vec4<f32>,
  /// }
  /// ```
  -/// if the fragment shader is left unspecified.
  +/// if the fragment module is left unspecified (default).
  ///
  /// Produce a Shader using [ShaderBuilder].
  ///
  