docs: mention -metrics.exposeMetadata command-line flag in Monitoring sections

This is a follow-up for 326a77c697

docs/README.md

@@ -2012,12 +2012,17 @@ mkfs.ext4 ... -O 64bit,huge_file,extent -T huge
 ## Monitoring
 
 VictoriaMetrics exports internal metrics in Prometheus exposition format at `/metrics` page.
-These metrics can be scraped via [vmagent](https://docs.victoriametrics.com/vmagent.html) or Prometheus.
+These metrics can be scraped via [vmagent](https://docs.victoriametrics.com/vmagent.html) or any other Prometheus-compatible scraper.
+
+If you use Google Cloud Managed Prometheus for scraping metrics from VictoriaMetrics components, then pass `-metrics.exposeMetadata`
+command-line to them, so they add `TYPE` and `HELP` comments per each exposed metric at `/metrics` page.
+See [these docs](https://cloud.google.com/stackdriver/docs/managed-prometheus/troubleshooting#missing-metric-type) for details.
+
 Alternatively, single-node VictoriaMetrics can self-scrape the metrics when `-selfScrapeInterval` command-line flag is 
 set to duration greater than 0. For example, `-selfScrapeInterval=10s` would enable self-scraping of `/metrics` page 
 with 10 seconds interval.
 
-_Please note, never use loadbalancer address for scraping metrics. All monitored components should be scraped directly by their address._
+_Please note, never use loadbalancer address for scraping metrics. All the monitored components should be scraped directly by their address._
 
 Official Grafana dashboards available for [single-node](https://grafana.com/grafana/dashboards/10229)
 and [clustered](https://grafana.com/grafana/dashboards/11176) VictoriaMetrics.

docs/Single-server-VictoriaMetrics.md

@@ -2020,12 +2020,17 @@ mkfs.ext4 ... -O 64bit,huge_file,extent -T huge
 ## Monitoring
 
 VictoriaMetrics exports internal metrics in Prometheus exposition format at `/metrics` page.
-These metrics can be scraped via [vmagent](https://docs.victoriametrics.com/vmagent.html) or Prometheus.
+These metrics can be scraped via [vmagent](https://docs.victoriametrics.com/vmagent.html) or any other Prometheus-compatible scraper.
+
+If you use Google Cloud Managed Prometheus for scraping metrics from VictoriaMetrics components, then pass `-metrics.exposeMetadata`
+command-line to them, so they add `TYPE` and `HELP` comments per each exposed metric at `/metrics` page.
+See [these docs](https://cloud.google.com/stackdriver/docs/managed-prometheus/troubleshooting#missing-metric-type) for details.
+
 Alternatively, single-node VictoriaMetrics can self-scrape the metrics when `-selfScrapeInterval` command-line flag is 
 set to duration greater than 0. For example, `-selfScrapeInterval=10s` would enable self-scraping of `/metrics` page 
 with 10 seconds interval.
 
-_Please note, never use loadbalancer address for scraping metrics. All monitored components should be scraped directly by their address._
+_Please note, never use loadbalancer address for scraping metrics. All the monitored components should be scraped directly by their address._
 
 Official Grafana dashboards available for [single-node](https://grafana.com/grafana/dashboards/10229)
 and [clustered](https://grafana.com/grafana/dashboards/11176) VictoriaMetrics.

docs/vmagent.md

@@ -1023,9 +1023,13 @@ See also [cardinality explorer docs](https://docs.victoriametrics.com/#cardinali
 ## Monitoring
 
 `vmagent` exports various metrics in Prometheus exposition format at `http://vmagent-host:8429/metrics` page.
-We recommend setting up regular scraping of this page either through `vmagent` itself or by Prometheus
+We recommend setting up regular scraping of this page either through `vmagent` itself or by Prometheus-compatible scraper,
 so that the exported metrics may be analyzed later.
 
+If you use Google Cloud Managed Prometheus for scraping metrics from VictoriaMetrics components, then pass `-metrics.exposeMetadata`
+command-line to them, so they add `TYPE` and `HELP` comments per each exposed metric at `/metrics` page.
+See [these docs](https://cloud.google.com/stackdriver/docs/managed-prometheus/troubleshooting#missing-metric-type) for details.
+
 Use official [Grafana dashboard](https://grafana.com/grafana/dashboards/12683) for `vmagent` state overview.
 Graphs on this dashboard contain useful hints - hover the `i` icon at the top left corner of each graph in order to read it.
 If you have suggestions for improvements or have found a bug - please open an issue on github or add a review to the dashboard.

docs/vmalert.md

@@ -790,8 +790,12 @@ See more details [here](https://docs.victoriametrics.com/vmalert-tool.html#Unit-
 
 `vmalert` exports various metrics in Prometheus exposition format at `http://vmalert-host:8880/metrics` page.
 The default list of alerting rules for these metric can be found [here](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/master/deployment/docker).
-We recommend setting up regular scraping of this page either through `vmagent` or by Prometheus so that the exported
+We recommend setting up regular scraping of this page either through [vmagent](https://docs.victoriametrics.com/vmagent.html) or by Prometheus-compatible scraper,
-metrics may be analyzed later.
+so that the exported metrics may be analyzed later.
+
+If you use Google Cloud Managed Prometheus for scraping metrics from VictoriaMetrics components, then pass `-metrics.exposeMetadata`
+command-line to them, so they add `TYPE` and `HELP` comments per each exposed metric at `/metrics` page.
+See [these docs](https://cloud.google.com/stackdriver/docs/managed-prometheus/troubleshooting#missing-metric-type) for details.
 
 Use the official [Grafana dashboard](https://grafana.com/grafana/dashboards/14950) for `vmalert` overview.
 Graphs on this dashboard contain useful hints - hover the `i` icon in the top left corner of each graph in order to read it.

docs/vmauth.md

@@ -693,7 +693,11 @@ It is recommended protecting the following endpoints with authKeys:
 ## Monitoring
 
 `vmauth` exports various metrics in Prometheus exposition format at `http://vmauth-host:8427/metrics` page. It is recommended setting up regular scraping of this page
-either via [vmagent](https://docs.victoriametrics.com/vmagent.html) or via Prometheus, so the exported metrics could be analyzed later.
+either via [vmagent](https://docs.victoriametrics.com/vmagent.html) or via Prometheus-compatible scraper, so the exported metrics could be analyzed later.
+
+If you use Google Cloud Managed Prometheus for scraping metrics from VictoriaMetrics components, then pass `-metrics.exposeMetadata`
+command-line to them, so they add `TYPE` and `HELP` comments per each exposed metric at `/metrics` page.
+See [these docs](https://cloud.google.com/stackdriver/docs/managed-prometheus/troubleshooting#missing-metric-type) for details.
 
 `vmauth` exports the following metrics per each defined user in [`-auth.config`](#auth-config):