reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/http-server/custom-httpserver/easy-way/main.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"net/http"
+
+	"github.com/kataras/iris/v12"
+)
+
+func main() {
+	app := iris.New()
+
+	app.Get("/", func(ctx iris.Context) {
+		ctx.Writef("Hello from the server")
+	})
+
+	app.Get("/mypath", func(ctx iris.Context) {
+		ctx.Writef("Hello from %s", ctx.Path())
+	})
+
+	// Any custom fields here. Handler and ErrorLog are set to the server automatically
+	srv := &http.Server{Addr: ":8080"}
+
+	// http://localhost:8080/
+	// http://localhost:8080/mypath
+	app.Run(iris.Server(srv)) // same as app.Listen(":8080")
+
+	// More:
+	// see "multi" if you need to use more than one server at the same app.
+	//
+	// for a custom listener use: iris.Listener(net.Listener) or
+	// iris.TLS(cert,key) or iris.AutoTLS(), see "custom-listener" example for those.
+}