README.md in redlock-1.1.0 vs README.md in redlock-1.2.0

@@ -1,13 +1,11 @@
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 # Redlock - A ruby distributed lock using redis.
 
 > Distributed locks are a very useful primitive in many environments where different processes require to operate  with shared resources in a mutually exclusive way.
@@ -135,9 +133,17 @@
                   retry_count:   3,
                   retry_delay:   200, # milliseconds
                   retry_jitter:  50,  # milliseconds
                   redis_timeout: 0.1  # seconds
                  })
+```
+
+It is possible to associate `:retry_delay` option with `Proc` object. It will be called every time, with attempt number
+as argument, to get delay time value before next retry.
+
+```ruby
+retry_delay = proc { |attempt_number| 200 * attempt_number ** 2 } # delay of 200ms for 1st retry, 800ms for 2nd retry, etc.
+lock_manager = Redlock::Client.new(servers, retry_delay: retry_delay)
 ```
 
 For more information you can check [documentation](http://www.rubydoc.info/gems/redlock/Redlock%2FClient:initialize).
 
 ## Run tests