Add instructions to add bots to the "Service Users" group
Add instructions to add bots to the "Service Users" group

Attention set behaves differently for users in that group, and
users that are not in the group. It's best to make sure that all
bots are in the Service Users group; such that they do not affect
the attention set.

Change-Id: I91194fbb8cbe7fafd1d74d751e5c764b258b5983

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