Remove separate V1 formatter from the read me.

README.mdown

@@ -183,7 +183,6 @@ Formatters
 - _ChromePHPFormatter_: Used to format log records into the ChromePHP format, only useful for the ChromePHPHandler.
 - _GelfFormatter_: Used to format log records into Gelf message instances, only useful for the GelfHandler.
 - _LogstashFormatter_: Used to format log records into [logstash](http://logstash.net/) event json, useful for any handler listed under inputs [here](http://logstash.net/docs/1.1.5/).
-- _LogstashV1Formatter_: Used to format log records into [logstash](http://logstash.net/)'s '[version 1](https://logstash.jira.com/browse/LOGSTASH-675)' event json (for 1.2.0 and newer).
 
 Processors
 ----------