[BUG] Support "go install"

[jayvdb]

Describe the bug
go install goa.design/model/cmd/stz@latest is ignored, even if no go.mod exists.

The usage of go install has changed over time. c.f. https://stackoverflow.com/questions/24878737/what-is-the-difference-between-go-get-and-go-install

To Reproduce
Steps to reproduce the behavior:

1. go install goa.design/model/cmd/stz@latest

Expected behavior
If there is no go.mod in the current directory, the install will be per-user

Desktop (please complete the following information):

• OS: Linux
• Shell: Bash

Additional context
I am increasingly seeing README's use go install.

Multiple sub_commands values are only used by nix and zypper , and in those cases the values are aliases, not separate commands with different flags.

Machine information