fix(ccn): [120885420] tencentcloud_ccn update doc and code (#2989)

* optimize doc

* add changelog

Author: hellertang

.changelog/2989.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+resource/tencentcloud_ccn: Modify the description of `qos`
+```

tencentcloud/services/ccn/resource_tc_ccn.go

@@ -46,7 +46,7 @@ func ResourceTencentCloudCcn() *schema.Resource {
 				ForceNew:     true,
 				Default:      CNN_QOS_AU,
 				ValidateFunc: tccommon.ValidateAllowedStringValue([]string{CNN_QOS_PT, CNN_QOS_AU, CNN_QOS_AG}),
-				Description:  "Service quality of CCN. Valid values: `PT`, `AU`, `AG`. The default is `AU`.",
+				Description:  "CCN service quality, 'PT': Platinum, 'AU': Gold, 'AG': Silver. The default is 'AU'.",
 			},
 			"charge_type": {
 				Type:         schema.TypeString,

website/docs/r/ccn.html.markdown

@@ -67,7 +67,7 @@ The following arguments are supported:
 * `bandwidth_limit_type` - (Optional, String) The speed limit type. Valid values: `INTER_REGION_LIMIT`, `OUTER_REGION_LIMIT`. `OUTER_REGION_LIMIT` represents the regional export speed limit, `INTER_REGION_LIMIT` is the inter-regional speed limit. The default is `OUTER_REGION_LIMIT`.
 * `charge_type` - (Optional, String, ForceNew) Billing mode. Valid values: `PREPAID`, `POSTPAID`. `PREPAID` means prepaid, which means annual and monthly subscription, `POSTPAID` means post-payment, which means billing by volume. The default is `POSTPAID`. The prepaid model only supports inter-regional speed limit, and the post-paid model supports inter-regional speed limit and regional export speed limit.
 * `description` - (Optional, String) Description of CCN, and maximum length does not exceed 100 bytes.
-* `qos` - (Optional, String, ForceNew) Service quality of CCN. Valid values: `PT`, `AU`, `AG`. The default is `AU`.
+* `qos` - (Optional, String, ForceNew) CCN service quality, 'PT': Platinum, 'AU': Gold, 'AG': Silver. The default is 'AU'.
 * `route_ecmp_flag` - (Optional, Bool) Whether to enable the equivalent routing function. `true`: enabled, `false`: disabled.
 * `route_overlap_flag` - (Optional, Bool) Whether to enable the routing overlap function. `true`: enabled, `false`: disabled.
 * `tags` - (Optional, Map) Instance tag.