doc: move metrics libs to device API section
doc: move metrics libs to device API section

The metrics headers were listed in misc section,
whereas they belong to the device API family.

Fixes: 349950ddb9c5 ("metrics: add information metrics library")
Fixes: 2ad7ba9a6567 ("bitrate: add bitrate statistics library")
Fixes: 5cd3cac9ed22 ("latency: added new library for latency stats")

Signed-off-by: Thomas Monjalon <5f50a84c1fa3bcff146405017f36aec1a10a9e38@monjalon.net>
Acked-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk