Move monitoring/ to new location

doc/README.md

doc/administration/monitoring/health_check.md

doc/administration/monitoring/img/health_check_token.png

...nistration/monitoring/performance/gitlab_configuration.md

...istration/monitoring/performance/grafana_configuration.md

...monitoring/performance/img/grafana_dashboard_dropdown.png

...n/monitoring/performance/img/grafana_dashboard_import.png

...ing/performance/img/grafana_data_source_configuration.png

.../monitoring/performance/img/grafana_data_source_empty.png

...stration/monitoring/performance/img/grafana_save_icon.png

...performance/img/metrics_gitlab_configuration_settings.png

...stration/monitoring/performance/influxdb_configuration.md

doc/administration/monitoring/performance/influxdb_schema.md

doc/administration/monitoring/performance/introduction.md

doc/monitoring/health_check.md

doc/monitoring/performance/gitlab_configuration.md

doc/monitoring/performance/grafana_configuration.md

doc/monitoring/performance/influxdb_configuration.md

doc/monitoring/performance/influxdb_schema.md

doc/monitoring/performance/introduction.md