☕ add a dependency-injection examples folder for the next release and some improvements

Former-commit-id: 040168afb7caf808618f7da5e68ae8eb01cb7170

_examples/dependency-injection/basic/main.go

@@ -0,0 +1,27 @@
+package main
+
+import "github.com/kataras/iris/v12"
+
+type (
+	testInput struct {
+		Email string `json:"email"`
+	}
+
+	testOutput struct {
+		ID   int    `json:"id"`
+		Name string `json:"name"`
+	}
+)
+
+func handler(id int, in testInput) testOutput {
+	return testOutput{
+		ID:   id,
+		Name: in.Email,
+	}
+}
+
+func main() {
+	app := iris.New()
+	app.HandleFunc(iris.MethodPost, "/{id:int}", handler)
+	app.Listen(":5000", iris.WithOptimizations)
+}