improve readme with example

README.md

@@ -1,3 +1,42 @@
 # GubGub
 
 Another Go PubSub library.
+
+## Getting started
+
+```sh
+go get -u gitlab.com/naterciom/gubgub
+```
+
+## Example
+
+```Go
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"gitlab.com/naterciom/gubgub"
+)
+
+type MyMessage struct {
+	Name string
+}
+
+func main() {
+	ctx, cancel := context.WithTimeout(context.TODO(), time.Second)
+	defer cancel()
+
+	topic := gubgub.NewAsyncTopic[MyMessage](ctx)
+
+	topic.Subscribe(gubgub.Forever(func(msg MyMessage) {
+		fmt.Printf("Hello %s", msg.Name)
+	}))
+
+	topic.Publish(MyMessage{Name: "John Smith"})
+
+	<-ctx.Done()
+}
+```