fix: maintenance doc (#1297)

Co-authored-by: arunma <arunma@tencent.com>

Author: gitmkn

tencentcloud/resource_tc_monitor_tmp_alert_rule.go

@@ -66,7 +66,7 @@ func resourceTencentCloudMonitorTmpAlertRule() *schema.Resource {
 			"expr": {
 				Type:        schema.TypeString,
 				Required:    true,
-				Description: "Rule expression.",
+				Description: "Rule expression, reference documentation: `https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/`.",
 			},
 			"receivers": {
 				Type:        schema.TypeSet,

website/docs/r/monitor_tmp_alert_rule.html.markdown

@@ -36,7 +36,7 @@ resource "tencentcloud_monitor_tmp_alert_rule" "tmpAlertRule" {
 
 The following arguments are supported:
 
-* `expr` - (Required, String) Rule expression.
+* `expr` - (Required, String) Rule expression, reference documentation: `https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/`.
 * `instance_id` - (Required, String) Instance id.
 * `receivers` - (Required, Set: [`String`]) Alarm notification template id list.
 * `rule_name` - (Required, String) Rule name.