Texture Mapping - Combined image sampler - Add vertex color back, correct repeat mode example

[rehlee]

Minor document updates:

• Add back the Vertex color and update text to match the code and make it consistent with the rest of the document. Removing the color from just the struct creates an error as it is still in the vertices array and shader. And it is still used in the last example.
• Correct repeat mode fragment shader example to match result image.

[CLAassistant]

All committers have signed the CLA.