Fixing listing in callback part of docs.

README.md

@@ -207,7 +207,7 @@ The first argument can be either a `url` or an `options` object. The only requir
 The callback argument gets 3 arguments: 
 
 1. An `error` when applicable (usually from the `http.Client` option, not the `http.ClientRequest` object)
-2.An `http.ClientResponse` object
+2. An `http.ClientResponse` object
 3. The third is the `response` body (`String` or `Buffer`)
 
 ## Convenience methods