Fix copyright notes.

Assets/HLSL/ClassicNoise2D.cginc

@@ -1,7 +1,7 @@
 //
 // Noise Shaders for Unity - https://github.com/keijiro/NoiseShader
 //
-// Original work (webgl-noise) Copyright (C) 2011 Ashima Arts.
+// Original work (webgl-noise) Copyright (C) 2011 Stefan Gustavson
 // Translation and modification was made by Keijiro Takahashi.
 //
 // This shader is based on the webgl-noise GLSL shader. For further details

Assets/HLSL/ClassicNoise3D.cginc

@@ -1,7 +1,7 @@
 //
 // Noise Shaders for Unity - https://github.com/keijiro/NoiseShader
 //
-// Original work (webgl-noise) Copyright (C) 2011 Ashima Arts.
+// Original work (webgl-noise) Copyright (C) 2011 Stefan Gustavson
 // Translation and modification was made by Keijiro Takahashi.
 //
 // This shader is based on the webgl-noise GLSL shader. For further details

README.md

@@ -1,6 +1,21 @@
-NoiseShader
-===========
+Noise Shaders for Unity
+=======================
 
-This is an HLSL variant of Gustavson's webgl-noise. For further details, see the original repository below.
+This is a noise shader library for Unity, which is based on the webgl-noise
+GLSL shaders written by Stefan Gustavson and Ahima Arts.
 
 https://github.com/ashima/webgl-noise
+
+Translations and modifications were made by Keijiro Takahashi.
+
+https://github.com/keijiro/NoiseShader
+
+This library provides the following types of functions written in HLSL:
+
+- Classic Perlin noise (2D/3D)
+- Periodic Perlin noise (2D/3D)
+- Simplex noise (2D/3D)
+- Analytical derivatives of simplex noise (2D/3D)
+
+The source code for these functions is released under the conditions of the
+MIT license. Please see the header of each file for details.