Improve the project description in the vgmspec171.txt file

[felipesanches]

Current descrition reads like:

"VGM (Video Game Music) is a sample-accurate sound logging format for the Sega
Master System, the Sega Game Gear and possibly many other machines (e.g. Sega
Genesis)."

But vgmplay actually supports a whole wider set of sound chips for several kinds of machines, including most arcade machines supported by MAME. It seems like the current description was written back when the program was in its early development stage. If the original author (or someone else) could confirm that, this may be an interesting fact about the development history of the program and a mention to it could possibly be kept in the file.

[vampirefrog]

I'd say hold off on this until ValleyBell has a look. He promised he'd commit some code as well. That file basically describes the VGM file format. VB is responsible for that.

[ValleyBell]

The description dates back to the VGM Spec. v1.50 from 2005. (I have also v1.01, which is even older and has almost the same wording.)

It's just that I never touched that part of the spec., so it remained unchanged since about 2002.