Propose update to master config file

Per the documentation: http://docs.saltstack.com/en/latest/ref/configuration/master.html#include-configuration  the include directive is unset by default.  As documented at the top of the master config file: "Values that are commented out but have no space after the comment are defaults that need not be set in the config. If there is a space after the comment that the value is presented as an example and is not the default."  Therefore, I propose adding a space after the comment to clarify that this is an example directive and not the default.
Merge pull request #18702 from wolfpackmars2/patch-1

Propose update to master config file