added yml/json/toml support, --help flag, and example directory

Signed-off-by: Andrey Nering <andrey.nering@gmail.com>

cmd/task/task.go

@@ -1,9 +1,34 @@
 package main
 
 import (
+	"flag"
+	"fmt"
+
 	"github.com/go-task/task"
 )
 
 func main() {
+	flag.CommandLine.Usage = func() {
+		fmt.Println(`
+task [target1 target2 ...]: Runs commands under targets like make.
+
+Example: 'task hello' with the following 'Taskfile.json' file will generate
+an 'output.txt' file.
+'''
+{
+  "hello": {
+    "cmds": [
+      "echo \"I am going to write a file named 'output.txt' now.\"",
+      "echo \"hello\" > output.txt"
+    ],
+    "generates": [
+      "output.txt"
+    ]
+  }
+}
+'''
+`)
+	}
+	flag.Parse()
 	task.Run()
 }