Embedded images for metrics documentation are broken

Problem

The embedded images on the documentation for our metrics server are broken: https://docs.gitlab.com/ee/operations/metrics/

Root cause

The page URL is https://docs.gitlab.com/ee/operations/metrics/. The images are referenced as img/metrics_list_v16_8.png.

This causes the resulting URL to be: https://docs.gitlab.com/ee/operations/metrics/img/metrics_list_v16_8.png

Unfortunately, this file does not exist here as the ../metrics/.. directory does not exist. The actual working URL is https://docs.gitlab.com/ee/operations/img/metrics_list_v16_8.png