docs: added versions_to_keep to config docs, #9671

docs/sources/installation/configuration.md

@@ -87,7 +87,7 @@ command line in the init.d script or the systemd service file.  It can
 be overridden in the configuration file or in the default environment variable
 file.
 
-### plugins 
+### plugins
 
 Directory where grafana will automatically scan and look for plugins
 
@@ -624,6 +624,12 @@ Analytics ID here. By default this feature is disabled.
 
 <hr />
 
+## [dashboards]
+
+### versions_to_keep (introduced in v5.0)
+
+Number dashboard versions to keep (per dashboard). Default: 20, Minimum: 1.
+
 ## [dashboards.json]
 
 If you have a system that automatically builds dashboards as json files you can enable this feature to have the