fix example code error (#204)

* fix example code error

* Update 09-selector.md

docs/component/09-selector.md

@@ -46,13 +46,13 @@ type Rebalancer interface {
 ### HTTP Client
 
 ```go
-import	"github.com/go-kratos/kratos/v2/selector/p2c"
+import	"github.com/go-kratos/kratos/v2/selector/wrr"
 import	"github.com/go-kratos/kratos/v2/selector/filter"
 
 // 创建路由 Filter：筛选版本号为"2.0.0"的实例
 filter :=  filter.Version("2.0.0")
 // 创建 P2C 负载均衡算法 Selector，并将路由 Filter 注入
-selector.SetGlobalSelector(wrr.NewBuilder)
+selector.SetGlobalSelector(wrr.NewBuilder())
 
 hConn, err := http.NewClient(
   context.Background(),
@@ -65,13 +65,13 @@ hConn, err := http.NewClient(
 ### gRPC Client
 
 ```go
-import	"github.com/go-kratos/kratos/v2/selector/p2c"
+import	"github.com/go-kratos/kratos/v2/selector/wrr"
 import	"github.com/go-kratos/kratos/v2/selector/filter"
 
 // 创建路由 Filter：筛选版本号为"2.0.0"的实例
 filter :=  filter.Version("2.0.0")
 // 由于 gRPC 框架的限制，只能使用全局 balancer name 的方式来注入 selector
-selector.SetGlobalSelector(wrr.NewBuilder)
+selector.SetGlobalSelector(wrr.NewBuilder())
 
 conn, err := grpc.DialInsecure(
   context.Background(),

i18n/en/docusaurus-plugin-content-docs/current/component/09-selector.md

@@ -46,13 +46,13 @@ Supported implementations:
 ### HTTP Client
 
 ```go
-import "github.com/go-kratos/kratos/v2/selector/p2c"
+import "github.com/go-kratos/kratos/v2/selector/wrr"
 import "github.com/go-kratos/kratos/v2/selector/filter"
 
 // Create a route Filter: filter instances with version number "2.0.0".
 filter := filter.Version("2.0.0")
 // Create P2C load balancing algorithm Selector, and inject routing Filter.
-selctor.SetGlobalSelector(wrr.NewBuilder)
+selctor.SetGlobalSelector(wrr.NewBuilder())
 
 hConn, err := http.NewClient(
   http.WithEndpoint("discovery:///helloworld"),
@@ -64,13 +64,13 @@ hConn, err := http.NewClient(
 ### gRPC Client
 
 ```go
-import "github.com/go-kratos/kratos/v2/selector/p2c"
+import "github.com/go-kratos/kratos/v2/selector/wrr"
 import "github.com/go-kratos/kratos/v2/selector/filter"
 
 // Create a route Filter: filter instances with version number "2.0.0".
 filter := filter.Version("2.0.0")
 // Due to the limitations of the gRPC framework, only the global balancer name can be used to inject Selector.
-selector.SetGlobalSelector(wrr.NewBuilder)
+selector.SetGlobalSelector(wrr.NewBuilder())
 
 conn, err := grpc.DialInsecure(
   context.Background(),