monasca-agent docs:for dpdk port metric tables is missing in Ovs.md file

[Ashish Kumar Gupta]

Actual :
Per-DHCP port Metrics and Per-DHCP Rate Metrics are available but
For https://review.openstack.org/#/c/328844/ doc should be updated including the dpdk port.

Added metric support for DPDK ports

Implemented the below metrics
vswitch.out_bytes
vswitch.in_bytes
vswitch.in_bits
vswitch.out_bits
vswitch.out_packets
vswitch.in_dropped
vswitch.out_dropped
vswitch.in_errors
vswitch.out_errors
vswitch.in_packets

vswitch.out_bytes_sec
vswitch.in_bytes_sec
vswitch.out_bits_sec
vswitch.in_bits_sec
vswitch.out_packets_sec
vswitch.in_dropped_sec
vswitch.out_dropped_sec
vswitch.in_errors_sec
vswitch.out_errors_sec
vswitch.in_packets_sec

MAy be the current doc can be generic for dhcp and dpdk port.