Outdated go command in Installation page

[szymczag]

Command

go get -u github.com/bettercap/bettercap

throws the error:

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'.

[rana-ans]

I added the new lines for the fix in my Pull Request, which lead to proper guidance of installation and running bettercap.

P.S. Thanks to the owners for this Repo!