Added DisconnectWorkersFromARunningDistributor.md

A document about how to disconnect a worker from a running distributor using powershell
Also "This way the distributor has a ready message in its storage queue for every message a worker can receive, and also it keeps in memory a list of workers with its session." not making a lot of sense.
Maybe this is too low level ? Do we really need it ? //cc @dannycohen @SimonCropp @indualagarsamy thoughts?