Merge branch 'update_prometheus_dashboard_yaml_properties_docs' into 'master'

Add max_value property to docs

See merge request gitlab-org/gitlab!29568

doc/user/project/integrations/prometheus.md

@@ -289,6 +289,7 @@ The following tables outline the details of expected properties.
 | `title` | string | yes | Heading for the panel. |
 | `y_label` | string | no, but highly encouraged | Y-Axis label for the panel. |
 | `y_axis` | string | no | Y-Axis configuration for the panel. |
+| `max_value` | number | no | Denominator value used for calculating [percentile based results](#percentile-based-results) |
 | `weight` | number | no, defaults to order in file | Order to appear within the grouping. Lower number means higher priority, which will be higher on the page. Numbers do not need to be consecutive. |
 | `metrics` | array | yes | The metrics which should be displayed in the panel. Any number of metrics can be displayed when `type` is `area-chart` or `line-chart`, whereas only 3 can be displayed when `type` is `anomaly-chart`. |