'go get' is no longer supported outside a module

[probonopd]

Please update the documentation, as following it fails with go 1.1.9.

% go get github.com/rapid7/go-get-proxied
go: go.mod file not found in current directory or any parent directory.
        'go get' is no longer supported outside a module.
        To build and install a command, use 'go install' with a version,
        like 'go install example.com/cmd@latest'
        For more information, see https://golang.org/doc/go-get-install-deprecation
        or run 'go help get' or 'go help install'.