Install command deprecated

[alu0101124896]

As you can see in the following snippet, the install command suggested in the README.md is now deprecated:

$ go get github.com/thefryscorer/schemer2
go get: installing executables with 'go get' in module mode is deprecated.
	Use 'go install pkg@version' instead.
	For more information, see https://golang.org/doc/go-get-install-deprecation
	or run 'go help get' or 'go help install'.

It now should be $ go install github.com/thefryscorer/schemer2@latest instead.

Aside from that, the program works as expected, thanks for it and for the step by step installation guides.