Fix incorrect --help output in README

This removes the not actually available log flags from the README. We
should really have those (#111), but at least it's less confusing this
way.

Fixes #110.

README.md

@@ -44,10 +44,6 @@ without values (`#some_tag`) are not supported.
     $ go build
     $ ./statsd_exporter --help
     Usage of ./statsd_exporter:
-      -log.format value
-            If set use a syslog logger or JSON logging. Example: logger:syslog?appname=bob&local=7 or logger:stdout?json=true. Defaults to stderr.
-      -log.level value
-            Only log messages with the given severity or above. Valid levels: [debug, info, warn, error, fatal].
       -statsd.listen-address string
           The UDP address on which to receive statsd metric lines. DEPRECATED, use statsd.listen-udp instead.
       -statsd.listen-tcp string