Documentation wrongly states default coordinator action timeout as -1 (should be 2 hrs)

Minor doc change to correct default value for coordinator action timeout (2 hr not -1 i.e. infinity)
http://oozie.apache.org/docs/4.2.0/CoordinatorFunctionalSpec.html#a6.3._Synchronous_Coordinator_Application_Definition

https://github.com/apache/oozie/blob/master/core/src/main/resources/oozie-default.xml#L524