Fix procedural examples

[ajlende]

Color spaces need to be registered for parse, convert, toGamut, and serialize to work in the procedural example. I was a bit surprised that I had to register LCH for toGamut to work, but if it uses LCH by default, I suppose it can't be avoided.

[LeaVerou]

Hey, thanks for pointing this out! That sounds like a bug we need to fix in the code, not the documentation.

[LeaVerou]

I mean, color spaces do need to be registered for parse() to work. For convert(), you can pass in a reference instead of a string. toGamut should import its own dependencies, I suspect the reason it doesn't right now is that you can choose to reduce via a different coordinate. serialize() should not need any color spaces to be registered?

[LeaVerou]

So I'm inclined to merge this, and we can always tweak in the future :) Thanks!