Update the documentation on charts with zero metrics (#6314)

collectors/cgroups.plugin/README.md

@@ -101,6 +101,15 @@ The whole point for the additional pattern list, is to limit the number of times
 
 The above pattern list is matched against the path of the cgroup. For matched cgroups, netdata calls the script [cgroup-name.sh](cgroup-name.sh.in) to get its name. This script queries `docker`, or applies heuristics to find give a name for the cgroup.
 
+### charts with zero metrics
+
+By default, Netdata will enable monitoring metrics only when they are not zero. If they are constantly zero they are ignored. Metrics that will start having values, after netdata is started, will be detected and charts will be automatically added to the dashboard (a refresh of the dashboard is needed for them to appear though). Set `yes` for a chart instead of `auto` to enable it permanently. For example:
+
+```
+[plugin:cgroups]
+	enable memory (used mem including cache) = yes
+```
+
 ### alarms
 
 CPU and memory limits are watched and used to rise alarms. Memory usage for every cgroup is checked against `ram` and `ram+swap` limits. CPU usage for every cgroup is checked against `cpuset.cpus` and `cpu.cfs_period_us` + `cpu.cfs_quota_us` pair assigned for the cgroup. Configuration for the alarms is available in `health.d/cgroups.conf` file.

collectors/diskspace.plugin/README.md

@@ -10,6 +10,9 @@ Two charts are available for every mount:
 
 Simple patterns can be used to exclude mounts from showed statistics based on path or filesystem. By default read-only mounts are not displayed. To display them `yes` should be set for a chart instead of `auto`.
 
+By default, Netdata will enable monitoring metrics only when they are not zero. If they are constantly zero they are ignored. Metrics that will start having values, after netdata is started, will be detected and charts will be automatically added to the dashboard (a refresh of the dashboard is needed for them to appear though). Set `yes` for a chart instead of `auto` to enable it permanently.
+
+
 ```
 [plugin:proc:diskspace]
     # remove charts of unmounted disks = yes

collectors/proc.plugin/README.md

@@ -75,7 +75,7 @@ netdata will automatically set the name of disks on the dashboard, from the moun
 
 ### performance metrics
 
-By default netdata will enable monitoring metrics only when they are not zero. If they are constantly zero they are ignored. Metrics that will start having values, after netdata is started, will be detected and charts will be automatically added to the dashboard (a refresh of the dashboard is needed for them to appear though).
+By default, Netdata will enable monitoring metrics only when they are not zero. If they are constantly zero they are ignored. Metrics that will start having values, after netdata is started, will be detected and charts will be automatically added to the dashboard (a refresh of the dashboard is needed for them to appear though). Set `yes` for a chart instead of `auto` to enable it permanently.
 
 netdata categorizes all block devices in 3 categories:
 

collectors/tc.plugin/README.md

@@ -191,6 +191,7 @@ Add the following configuration option in `/etc/netdata.conf`:
 Finally, create `/etc/netdata/tc-qos-helper.conf` with this content:
 ```tc_show="class"```
 
+Please note, that by default Netdata will enable monitoring metrics only when they are not zero. If they are constantly zero they are ignored. Metrics that will start having values, after netdata is started, will be detected and charts will be automatically added to the dashboard (a refresh of the dashboard is needed for them to appear though). Set `yes` for a chart instead of `auto` to enable it permanently.
 
 
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daemon/config/README.md

@@ -128,6 +128,8 @@ The configuration options for plugins appear in sections following the pattern `
 
 Most internal plugins will provide additional options. Check [Internal Plugins](../../collectors/) for more information.
 
+Please note, that by default Netdata will enable monitoring metrics for disks, memory, and network only when they are not zero. If they are constantly zero they are ignored. Metrics that will start having values, after netdata is started, will be detected and charts will be automatically added to the dashboard (a refresh of the dashboard is needed for them to appear though). Use `yes` instead of `auto` in plugin configuration sections to enable these charts permanently.
+
 #### External plugins
 
 External plugins will have only 2 options at `netdata.conf`:

docs/configuration-guide.md

@@ -57,6 +57,10 @@ Entire plugins can be turned off from the [netdata.conf [plugins]](../daemon/con
 - `node.d.conf` for [nodejs](../collectors/node.d.plugin/#nodedplugin)
 - `charts.d.conf` for [bash](../collectors/charts.d.plugin/#chartsdplugin)
 
+##### Show charts with zero metrics
+
+By default, Netdata will enable monitoring metrics for disks, memory, and network only when they are not zero. If they are constantly zero they are ignored. Metrics that will start having values, after netdata is started, will be detected and charts will be automatically added to the dashboard (a refresh of the dashboard is needed for them to appear though). Use `yes` instead of `auto` in plugin configuration sections to enable these charts permanently.
+
 ### Modify alarms and notifications
 
 ##### Add a new alarm