gl_shader: better comment for GLShader_generic2D

Author: illwieckz

src/engine/renderer/gl_shader.h

@@ -3915,9 +3915,7 @@ class GLShader_generic :
 	void SetShaderProgramUniforms( shaderProgram_t *shaderProgram ) override;
 };
 
-// This is just a copy of the GLShader_generic, but with a special
-// define for RmlUI transforms. It probably has a lot of unnecessary
-// code that could be pruned.
+// Has special code for RmlUi transforms.
 class GLShader_generic2D :
 	public GLShader,
 	public u_ColorMap,