Update tut5.rst

For rpyc 3.2.3, if FileMonitorService extends rpyc.Service, I get an error when attempting to connect: 'FileMonitorService' object has no attribute 'exposed_getmodule'

...However extending from rpyc.SlaveService makes the problem go away.
Merge pull request #126 from cuddihyd/patch-1

Update tut5.rst