improve comments in ogl3-texture.c
improve comments in ogl3-texture.c

runewake2/opengl-examples,JohnRThomas/opengl-examples,runewake2/opengl-examples,runewake2/opengl-examples,runewake2/opengl-examples,JohnRThomas/opengl-examples,JohnRThomas/opengl-examples,JohnRThomas/opengl-examples