docs:add configuration of namespace in docs

spring-cloud-tencent-docs/src/main/doc-zh/spring-cloud-tencent-polaris-discovery.md

@@ -83,10 +83,11 @@ spring:
 ## 配置列表
 
 | 配置项Key                                          | 默认值                        | 是否必填 | 配置项说明                     |
-| ----------------------------------------------- | -----------------------| --------- | ---------------------------- |
+|-------------------------------------------------|----------------------------|------|---------------------------|
 | spring.cloud.polaris.server-addr                | 无                          | 是    | Polaris后端地址               |
 | spring.cloud.polaris.discovery.service          | ${spring.application.name} | 否    | 服务名称                      |
 | spring.cloud.polaris.discovery.enabled          | true                       | 否    | 是否开启服务注册与发现               |
+| spring.cloud.polaris.discovery.namespace        | default                    | 否    | 服务所在的命名空间名称               |
 | spring.cloud.polaris.discovery.instance-enabled | true                       | 否    | 当前微服务实例是否可以被访问            |
 | spring.cloud.polaris.discovery.token            | 无                          | 否    | 鉴权Token                   |
 | spring.cloud.polaris.discovery.version          | null                       | 否    | 微服务版本                     |

spring-cloud-tencent-docs/src/main/doc/spring-cloud-tencent-polaris-discovery.md

@@ -80,10 +80,11 @@ Taking examples like random weight policy, you can add weight at Polaris control
 ## Configuration LIst
 
 | ConfigurationKey                                | default                    | Yes/No required | Configuration Instruction                            |
-| ----------------------------------------------- | -------------------------- | --------------- | ---------------------------------------------------- |
+|-------------------------------------------------|----------------------------|-----------------|------------------------------------------------------|
 | spring.cloud.polaris.server-addr                | false                      | yes             | Polaris backend address                              |
 | spring.cloud.polaris.discovery.service          | ${spring.application.name} | null            | service name                                         |
 | spring.cloud.polaris.discovery.enabled          | true                       | false           | whether to active service registration and discovery |
+| spring.cloud.polaris.discovery.namespace        | default                    | false           | the namespace of service                             |
 | spring.cloud.polaris.discovery.instance-enabled | true                       | false           | can current Microservice be visited                  |
 | spring.cloud.polaris.discovery.token            | false                      | false           | Authentication Token                                 |
 | spring.cloud.polaris.discovery.version          | null                       | false           | Microservice Version                                 |

spring-cloud-tencent-starters/spring-cloud-starter-tencent-polaris-discovery/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -10,7 +10,7 @@
       "name": "spring.cloud.polaris.discovery.namespace",
       "type": "java.lang.String",
       "defaultValue": "default",
-      "description": "the namespace of service, default value is ${spring.application.name}."
+      "description": "the namespace of service, default value is \"default\"."
     },
     {
       "name": "spring.cloud.polaris.discovery.enabled",