Impruve docs (#7)

* Add Usage Example (close #4)

* Add Contribute Note (close #5)

* add godocs docu

README.md

@@ -8,3 +8,26 @@
 
 ## ToDo
 * [ ] Predefine standard colors (red, blue, ... based on CSS colors)
+
+## Usage
+
+Download: `go get -u github.com/6543/go-hexcolor`
+
+Example:
+```go
+import (
+	"fmt"
+	"github.com/6543/go-hexcolor"
+)
+
+func main() {
+	c, err := hexcolor.NewHexColor("#adf")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(c.ToString())
+}
+```
+
+## Contribution
+Fork repository, clone it, make changes, push to new branch and submit a pull request.

doc.go

@@ -0,0 +1,33 @@
+// Copyright 2020 6543. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+/*
+
+Package hexcolor is a simple hexcolor normalizer
+
+Installation
+
+    go get -u github.com/6543/go-hexcolor
+
+Example
+
+    ```go
+    package main
+
+    import (
+    	"fmt"
+    	"github.com/6543/go-hexcolor"
+    )
+
+    func main() {
+    	c, err := hexcolor.NewHexColor("#adf")
+    	if err != nil {
+    		panic(err)
+    	}
+    	fmt.Println(c.ToString())
+    }
+    ```
+
+*/
+package hexcolor

hexcolor.go

@@ -1,3 +1,7 @@
+// Copyright 2020 6543. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
 package hexcolor
 
 import (

hexcolor_test.go

@@ -1,3 +1,7 @@
+// Copyright 2020 6543. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
 package hexcolor
 
 import (