The discovery rules page can be accessed via The Configure Menu:
Configure > Discovery rules
The discovery rules page exists to list any discovery rules. Such rules can be used to provision a set of hosts that have similar facts with the same configuration. In particular they allow for the automatic assignment of discovered hosts to a host group and a context (see also Host Groups and/or The Context Menu). They also allow the hostname to be set dynamically using the eRuby-template language.