Requesto for new lint: Recommend `uname -n` in place of a plain `hostname`

[slatian]

For new checks and feature suggestions

• https://www.shellcheck.net/ (i.e. the latest commit) currently gives no useful warnings about this
• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related requesting this feature

Here's a snippet or screenshot that shows a potential problem:

#!/bin/sh
printf "You are on host %s" "$(hostname)"

Here's what shellcheck currently says:

Nothing

Here's what I wanted to see:

Shellcheck should flag this use of hostname as non POSIX (see also issue #3468) and recommend uname -n instead (not that this does not include other usecases of the hostname command like setting the hostname).