Update "About" screen to remove R from PhET

[kathy-phet]

The PhET says ® on it in the 'About' screen. We still want to indicate that this is our trademark so change that line to read ...

PhET™ Interactive Simulations

I also reviewed the link to Terms, Privacy, and Licensing, and while that says we are a registered trademark, I think it is fine. We are registered, and people should know that. The main issue is that our sims our used in so many places we don't want the R symbol to be viewed as a marketing piece in these countries, and violate local laws. This webpage lives on our website, served from our country.

[samreid]

I pushed a proposed fix. In context it looks like this:

The previous unicode for (R) was also embedded in a <sup> superscript. I also tried that for the TM but it made it very high and tiny:

So I've committed without the <sup> since it looks like the TM is already rendered kind of like a superscript.

Leaving assigned to @ariel-phet and reassigning to @kathy-phet for review and feedback. You can see it live on phettest.

[kathy-phet]

I think I prefer the non-sup version, but could go either way. @ariel-phet - do you have a preference here?

[ariel-phet]

non-sup is the way to go @samreid