docs: Update metrics documentation with new metric
docs: Update metrics documentation with new metric

Signed-off-by: Aditi Ghag <436242e0c0af36e461a395c937165372864a99f9@cilium.io>

cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium