docs: use 'go install' instead of 'go get'

[mikaello]

As of Go 1.17, 'go get' is deprecated, and as of 1.18 'go get' will no longer build packages. 'go install' should be used instead, see https://go.dev/doc/go-get-install-deprecation

Signed-off-by: mikaello 2505178+mikaello@users.noreply.github.com

[pgporada]

You'll probably want to add @latest like the error message below.

$ go install github.com/ofabry/go-callvis
go: 'go install' requires a version when current directory is not in a module
	Try 'go install github.com/ofabry/go-callvis@latest' to install the latest version

[mikaello]

You'll probably want to add @latest like the error message below.

Thanks, fixed now.

[ondrajz]

Thank you.