Update README.md

[jasonwbarnett]

Description

This omnibus_server resource uses the ::PRODUCT_MATRIX global in mixlib-install to automatically fetch the ctl_command that should be used. The current example references chef-server-core which is no longer present in ::PRODUCT_MATRIX. This PR just updates the example(s) in the README.md so they are accurate.

• https://github.com/chef-cookbooks/chef-ingredient/blob/b3b29b991d87555c5e7ccd0f06703b02695fffd8/libraries/helpers.rb#L44-L51
• https://github.com/chef-cookbooks/chef-ingredient/blob/b3b29b991d87555c5e7ccd0f06703b02695fffd8/resources/omnibus_service.rb#L35-L42

Issues Resolved

N/A

Check List

• [ ] All tests pass. See https://github.com/chef-cookbooks/community_cookbook_documentation/blob/master/TESTING.MD
• [ ] New functionality includes testing.
• [x] New functionality has been documented in the README if applicable
• [ ] All commits have been signed for the Developer Certificate of Origin. See https://github.com/chef-cookbooks/community_cookbook_documentation/blob/master/CONTRIBUTING.MD

[tas50]

Thanks @jasonwbarnett