CEP18 / Documentation Update "Hash Types"

[RBYGLLS]

This ticket captures the effort to make the necessary updates regarding the "upgrade mechanism" for cep-18 into the existing and tutorials.

https://github.com/casper-ecosystem/cep18/blob/dev/cep18/src/main.rs#L363-L391
https://github.com/casper-ecosystem/cep18/pull/113

[ACStone-MTS]

@RBYGLLS I might be missing something, but both of those links are showing up as invalid to me.

[RBYGLLS]

@ACStoneCL Did you try to copy and pasting the URL into a browser?

[ACStone-MTS]

@RBYGLLS That did it, thanks!