Add the github requirements to the setup command
Add the github requirements to the setup command

The docs [here](https://www.habitat.sh/docs/developing-packages/#write-plans)
say to run the setup command and follow the instructions but the
instructions are incomplete. Instead of putting the access token
instructions in the other docs I decided to centralize them in the
command run.

Signed-off-by: David Aronsohn <e44d276949ba4ab4193cf1662f2d7af26a1537f2@Me.com>

rsertelon/habitat,georgemarshall/habitat,habitat-sh/habitat,habitat-sh/habitat,nathenharvey/habitat,habitat-sh/habitat,rsertelon/habitat,nathenharvey/habitat,nathenharvey/habitat,habitat-sh/habitat,nathenharvey/habitat,habitat-sh/habitat,georgemarshall/habitat,rsertelon/habitat,nathenharvey/habitat,georgemarshall/habitat,georgemarshall/habitat,rsertelon/habitat,habitat-sh/habitat,georgemarshall/habitat,georgemarshall/habitat,rsertelon/habitat,nathenharvey/habitat,georgemarshall/habitat,habitat-sh/habitat,georgemarshall/habitat,rsertelon/habitat,rsertelon/habitat,habitat-sh/habitat