docs: add an example using the Go module (#468)

example_test.go

@@ -0,0 +1,21 @@
+package mercure_test
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/dunglas/mercure"
+)
+
+func Example() {
+	h, err := mercure.NewHub(
+		mercure.WithPublisherJWT([]byte("!ChangeMe!"), "HS256"),
+		mercure.WithSubscriberJWT([]byte("!ChangeMe!"), "HS256"),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	http.Handle("/.well-known/mercure", h)
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}

hub.go

@@ -1,3 +1,5 @@
+// Package mercure helps implementing the Mercure protocol (https://mercure.rocks) in Go projects.
+// It provides an implementation of a Mercure hub as a HTTP handler.
 package mercure
 
 import (