Installing on alternate architectures

I wanted to install packer on a Linux machine with arm64 (aarch) architecture. When I just used apt-get install packer I got a dusty old version which I couldn’t use. I followed the steps at Installing Packer and it packer wasn’t upgraded. Then I noticed that amd64 was hardcoded in the command to add the repository:

sudo apt-add-repository "deb [arch=amd64] $(lsb_release -cs) main"

I ran another command, changing this to arm64 and got a more recent version like I was expecting.

Might I suggest that the instructions be improved to detect the native machine architecture? Thanks.