Fix path to config when OXIDIZED_HOME is set

This bug was discovered while working on issue #3255

lib/oxidized/config.rb

@@ -65,7 +65,7 @@ def self.load(cmd_opts = {})
         raise InvalidConfig, "Error loading config: #{e.message}"
       end
 
-      raise NoConfig, 'edit ~/.config/oxidized/config' if asetus.create
+      raise NoConfig, "edit #{ROOT}/config" if asetus.create
 
       # override if comand line flag given
       asetus.cfg.debug = cmd_opts[:debug] if cmd_opts[:debug]