Merge pull request #778 from eimlav/update-limitations

(MODULES-7622) - Update README Limitations section

README.md

@@ -556,10 +556,10 @@ All parameters are optional.
 
 ## Limitations
 
-This module is tested and officially supported on Debian 8 and 9 and Ubuntu 14.04, and 16.04. Testing on other platforms has been light and cannot be guaranteed.
-
 This module is not designed to be split across [run stages](https://docs.puppetlabs.com/puppet/latest/reference/lang_run_stages.html).
 
+For an extensive list of supported operating systems, see [metadata.json](https://github.com/puppetlabs/puppetlabs-apt/blob/master/metadata.json)
+
 ### Adding new sources or PPAs
 
 If you are adding a new source or PPA and trying to install packages from the new source or PPA on the same Puppet run, your `package` resource should depend on `Class['apt::update']`, in addition to depending on the `Apt::Source` or the `Apt::Ppa`. You can also add [collectors](https://docs.puppetlabs.com/puppet/latest/reference/lang_collectors.html) to ensure that all packages happen after `apt::update`, but this can lead to dependency cycles and has implications for [virtual resources](https://docs.puppetlabs.com/puppet/latest/reference/lang_collectors.html#behavior).