add a hello-world example as we had before, we have overview too but it's a little larger and newcomers may afraid 👍

Former-commit-id: 459d70bb690844176177050e37c24e28587f343b

_examples/beginner/hello-world/main.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"github.com/kataras/iris"
+	"github.com/kataras/iris/context"
+)
+
+func main() {
+	app := iris.New()
+	app.Handle("GET", "/", func(ctx context.Context) {
+		ctx.HTML("<b> Hello world! </b>")
+	})
+	app.Run(iris.Addr(":8080"))
+}