Fix attribute name to match recipe

Author: Matt Whiteley

README.md

@@ -64,7 +64,7 @@ want to restrict your node to using the `apt-cacher-ng` server in your
 Environment, set `['apt']['cacher-client']['restrict_environment']` to `true`.
 
 To use a cacher server (or standard proxy server) not available via search
-set the atttribute `['apt']['cacher-ipaddress']` and for a custom port
+set the atttribute `['apt']['cacher_ipaddress']` and for a custom port
 set `['apt']['cacher_port']`.
 
 Resources/Providers