Move integration/metrics to monitoring/performance

[ci skip]

doc/README.md

@@ -67,7 +67,7 @@
 - [Reply by email](incoming_email/README.md) Allow users to comment on issues and merge requests by replying to notification emails.
 - [Migrate GitLab CI to CE/EE](migrate_ci_to_ce/README.md) Follow this guide to migrate your existing GitLab CI data to GitLab CE/EE.
 - [Git LFS configuration](workflow/lfs/lfs_administration.md)
-- [GitLab Performance Monitoring](integration/metrics/introduction.md) Configure GitLab and InfluxDB for measuring performance metrics
+- [GitLab Performance Monitoring](monitoring/performance/introduction.md) Configure GitLab and InfluxDB for measuring performance metrics
 
 ## Contributor documentation