docs: Expose endpoint and policy computation time metrics
docs: Expose endpoint and policy computation time metrics

This commit adds doc changes to export endpoint and policy computation time
metrics to prometheus.

Fixes: #4396
Signed-Off-By: Manali Bhutiyani <f91afadb65fa57d2313cebbfecb7de1f482fe10f@covalent.io>

cilium-team/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,tklauser/cilium,tklauser/cilium,eloycoto/cilium,eloycoto/cilium,scanf/cilium,eloycoto/cilium,cilium/cilium,tgraf/cilium,scanf/cilium,scanf/cilium,tgraf/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium,eloycoto/cilium,eloycoto/cilium,tgraf/cilium,tklauser/cilium,tklauser/cilium,eloycoto/cilium,scanf/cilium,michi-covalent/cilium,eloycoto/cilium,cilium/cilium,tgraf/cilium,scanf/cilium,cilium-team/cilium,scanf/cilium,cilium/cilium,cilium/cilium,tgraf/cilium,scanf/cilium,tgraf/cilium