Fix mistake in README example

Author: Enric Sala

README.md

@@ -136,7 +136,7 @@ result = influxdb.query('weather') ...
     .execute();
 
 % Another example with more options
-result = influxdb.query(TEST_TAGS) ...
+result = influxdb.query('weather') ...
     .fields('mean(temperature)', 'sum(rain)') ...
     .groupByTags('country', 'city') ...
     .groupByTime('3h', 'linear') ...