BUG #17331: Minor change in install steps

The following bug has been logged on the website:

Bug reference: 17331
Logged by: Abhishek Nigam
Email address: abhisheknigam1996(at)gmail(dot)com
PostgreSQL version: 14.1
Operating system: Linux Mint 20.2
Description:

I was trying to install Postgres on my computer, by following steps
mentioned at https://www.postgresql.org/download/linux/ubuntu/

But on step,
# Update the package lists:
sudo apt-get update

It was failing with error message
Skipping acquire of configured file 'main/binary-i386/Packages' as
repository 'http://apt.postgresql.org/pub/repos/apt focal-pgdg InRelease'
doesn't support architecture 'i386'

I found the solution here -
https://stackoverflow.com/questions/61523447/skipping-acquire-of-configured-file-main-binary-i386-packages

I feel, since majority of the users are on amd64 architecture, in the
install steps we can mention
sudo sh -c 'echo "deb [arch=amd64] http://apt.postgresql.org/pub/repos/apt
$(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
instead of
sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt $(lsb_release
-cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'

Or we can add a note in the install steps that this command will have this
slight changes for users on this architecture.
I think it would make it easier for beginners to install Postgres.

Thank you for your work!

Abhishek