Note Pacemaker is the Project Successor of "Heartbeat Version 2".
If you are looking for documentation and information for the "Version 2" heartbeat, you should really be reading the Pacemaker home page at http://clusterlabs.org.
If you are stuck with Heartbeat 2.1.3 or Heartbeat 2.1.4, the best fitting Documentation is probably that for Pacemaker 0.6, which can also be found on the Pacemaker Documentation page
Quoting the first paragraph from v2 (in this wiki):
Heartbeat 2.1.4 was the last release to contain the CRM or "Version 2 Resource Manager" and since then all development and maintenance is performed as part of the Pacemaker project and all CRM code has been removed from Heartbeat.
For more details on Pacemaker, including latest versions, installation details and documentation, please visit http://clusterlabs.org.