Fix tutorial code snippet for passing coord

[nickcosmo]

Description

I noticed in the Introduction to Shaders page under the "Passing data from vertex to fragment shader" tutorial, the code snippet for the vertex shader was missing a line to pass the coord variable to the fragment shader and was instead passing an unused color variable.

I did not create an issue for this as it was such a small change.

Changes

• Update line to pass of the coord variable to the fragment shader
• Remove the vertex color variable which seemed to be not relevant to the code example.

Screenshots

Before

After