dfinkel: add a printing example for GopherCon

This commit adds a very useful tool, and it may or may not be live.

Change-Id: I543c9a66cd65c66685c900262ef4133d11ba0baa
Reviewed-on: https://go-review.googlesource.com/132324
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

dfinkel/main.go

@@ -0,0 +1,12 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Live from GopherCon, it's Thursday something!")
+	fmt.Println("Or, maybe not live anymore")
+}