Add Google Premier to README.

README.rdoc

@@ -268,6 +268,7 @@ Languages:: ar, eu, bg, bn, ca, cs, da, de, el, en, en-AU, en-GB, es, eu, fa, fi
 Documentation:: http://code.google.com/apis/maps/documentation/geocoding/#JSON
 Terms of Service:: http://code.google.com/apis/maps/terms.html#section_10_12
 Limitations:: "You must not use or display the Content without a corresponding Google map, unless you are explicitly permitted to do so in the Maps APIs Documentation, or through written permission from Google." "You must not pre-fetch, cache, or store any Content, except that you may store: (i) limited amounts of Content for the purpose of improving the performance of your Maps API Implementation..."
+Notes:: To use Google Premier set <tt>Geocoder::Configuration.lookup = :google_premier</tt> and <tt>Geocoder::Configuration.api_key = [key, client, channel]</tt>.
 
 ==== Yahoo (<tt>:yahoo</tt>)