docs(event): Added README.md (#84)

Signed-off-by: Flc゛ <[email protected]>

event/README.md

@@ -0,0 +1,68 @@
+# Event
+
+## Usage
+
+```go
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/go-kratos-ecosystem/components/v2/event"
+	"github.com/go-kratos-ecosystem/components/v2/feature"
+)
+
+type testListener struct {
+	feature.AsyncFeature  // async feature
+}
+
+func (l *testListener) Listen() []event.Event {
+	return []event.Event{
+		"test",
+		"test2",
+	}
+}
+
+func (l *testListener) Handle(e event.Event, data interface{}) {
+	if s, ok := data.(string); ok {
+		fmt.Println("event:", e, "data:", s)
+	} else {
+		panic("invalid data")
+	}
+}
+
+type test2Listener struct{}
+
+func (l *test2Listener) Listen() []event.Event {
+	return []event.Event{
+		"test",
+	}
+}
+
+func (l *test2Listener) Handle(event event.Event, data interface{}) {
+	fmt.Println("event:", event, "data:", data)
+}
+
+func main() {
+	d := event.NewDispatcher(event.WithRecovery(func(err interface{}, listener event.Listener, event event.Event, data interface{}) { //nolint:lll
+		fmt.Println("err:", err, "listener:", listener, "event:", event, "data:", data)
+	}))
+
+	d.AddListener(new(testListener), new(test2Listener))
+
+	d.Dispatch("test", "test data")
+	d.Dispatch("test2", "test2 data")
+	d.Dispatch("test3", "test3 data")
+
+	time.Sleep(time.Second)
+}
+```
+
+Output:
+
+```bash
+event: test data: test data
+event: test2 data: test2 data
+event: test data: test data
+```