Add documentation for com.cloudbees.hudson.plugins.folder.computed.ThrottleComputationQueueTaskDispatcher.LIMIT

regarding : https://groups.google.com/d/topic/jenkinsci-users/AnqZCSyQ-ek/discussion

It is not easy to find the information about how to increase or decrease the number of bitbucket analysers on jenkins master. Setting the env var com.cloudbees.hudson.plugins.folder.computed.ThrottleComputationQueueTaskDispatcher.LIMIT works but the information is only available in the code (https://github.com/jenkinsci/cloudbees-folder-plugin/blob/master/src/main/java/com/cloudbees/hudson/plugins/folder/computed/ThrottleComputationQueueTaskDispatcher.java).

Can you add documentation in the README of the repository or in https://go.cloudbees.com/docs/plugins/folder/ ?