Clarify on node groups that the groups are defined in the master config file, link to compound matchers.

[gravyboat]

http://docs.saltstack.com/topics/targeting/nodegroups.html is a little bit vague regarding where you define the node groups. While you can follow the link over to the master config page, it should be clearly explained in the 'here is an example' sentence that the example goes into /etc/salt/master. In addition the compound matcher sentence should either be modified, or moved, as currently it doesn't seem to 'flow' very well, and new users could miss what the L and G are equal to. Adding a note, as opposed to that line might make things a bit more clear.

[basepi]

Thanks! We'll get this added.