Tweak clearcoat wording & formatting a bit.

[emackey]

Fixed a word wrap issue, and tried to clarify the essence of what prompted the recent formula change.

[UX3D-nopper]

The resulting f_clearcoat color is expected to have a Fresnel term blended into it as a result of the above. is for me just confusing/obsolete. We are mentioning F, but not G or D or the dot products either.

[emackey]

Is there some way we can reword this just to convey why we changed the formula?

This extension uses a different formula than Substance Painter, for example, and yet the results look very, very similar, nearly pixel-perfect similar in certain situations. In SP clearcoat calls their pbrComputeSpecular(...) with a specular color of vec3(1.0) instead of our vec3(0.04). Then they use the Fresnel 0.04 term in a mix statement the way we had originally specified here. It's just a question of where the Fresnel 0.04 comes into clearcoat coloring, either before mixing with the base layer, or during the mix.

During the email chain we had several people ask if f_clearcoat already included that term or not, and confusion over that led us to change the formula. I think we need to say something to clarify that (and it sounds like I didn't accomplish that here, can someone suggest better wording please?)

[UX3D-nopper]

Let's asks the others later today.

[emackey]

The offending sentence was removed, so this PR is mostly error correction and formatting changes now. I'm merging it time for today's meeting.

As a reminder, new PRs for issues discussed here are still welcome after ratification so long as they don't change the IP.