doc: add eventdev library to programmers guide
This commit adds an entry in the programmers guide
explaining the eventdev library.
The rte_event struct, queues and ports are explained.
An API walktrough of a simple two stage atomic pipeline
provides the reader with a step by step overview of the
expected usage of the Eventdev API.
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Signed-off-by: David Hunt <david.hunt@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>