Add archlinux beaker example

Add a "none" beaker puppet collection example. i.e for OSes that
install the distro provided package.

moduleroot/.github/CONTRIBUTING.md.erb

@@ -245,6 +245,14 @@ with:
 BEAKER_PUPPET_COLLECTION=puppet7 BEAKER_setfile=debian11-64 bundle exec rake beaker
 ```
 
+or
+
+```sh
+BEAKER_PUPPET_COLLECTION=none BEAKER_setfile=archlinux-64 bundle exec rake beaker
+```
+
+This latter example will use distribution's own version of Puppet.
+
 You can replace the string `debian11` with any common operating system.
 The following strings are known to work:
 
@@ -254,6 +262,7 @@ The following strings are known to work:
 * centos7
 * centos8
 * centos9
+* archlinux
 * almalinux8
 * almalinux9
 * fedora36