use packr2 in command line about packr

[sio4]

Hi @TQuy,

It seems like the document you are referring to is somewhat outdated from some perspectives:

1. When installing a module with a command, in go1.18, the old method go get is deprecated. (see [1]) You can use the following command:

   go install github.com/gobuffalo/packr/v2/packr2@latest

   For the command installation, as your error message told you, the path to the main package should be provided as an argument for the install command and the path for the packr2 is like above.

2. More important change (for us): Packr was deprecated and not maintained now. For the (almost) same purpose of the file embedding, now you can use the go standard library's embed package so no more third-party packages are required for the file embedding. (see [2])

   All buffalo families are also migrated to the standard embed, and this repository will be archived soon. :-)

[1] https://tip.golang.org/doc/go1.18#go-get:~:text=go%20get%20no%20longer%20builds%20or%20installs%20packages%20in%20module%2Daware%20mode.
[2] https://pkg.go.dev/embed