Is there any documents for Demos?

HI, guys:
    I started OpenGL ES 2.0 learning few days ago. and I only found a simple shader training in <Migration from OpenGL ES 1.x to OpenGL ES 2.0 API.1.1f.External>. it’s useful for basic shader study, but it is hard to understand the complex skills like FOB in demo “Render to Texture”, light map, reflection and so on. so, is there any other docs to explain them ? thanks very much!