add LICENSE file

Make the MIT license easier to see by adding a LICENSE file.
Use the template at https://choosealicense.com/licenses/mit.

Also regenerate .travis.yml and README.md files with gorepogen.

Fixes #1.

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2016 Dmitri Shuralyov
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -1,29 +1,30 @@
 tictactoe
 =========
 
-[![Build Status](https://travis-ci.org/shurcooL/tictactoe.svg?branch=master)](https://travis-ci.org/shurcooL/tictactoe) [![GoDoc](https://godoc.org/github.com/shurcooL/tictactoe?status.svg)](https://godoc.org/github.com/shurcooL/tictactoe)
+[![Go Reference](https://pkg.go.dev/badge/github.com/shurcooL/tictactoe.svg)](https://pkg.go.dev/github.com/shurcooL/tictactoe)
+[![Build Status](https://travis-ci.org/shurcooL/tictactoe.svg?branch=master)](https://travis-ci.org/shurcooL/tictactoe)
 
 Package tictactoe defines the game of tic-tac-toe.
 
 Installation
 ------------
 
 ```bash
-go get -u github.com/shurcooL/tictactoe
+go get github.com/shurcooL/tictactoe
 ```
 
 Directories
 -----------
 
-| Path                                                                             | Synopsis                                                      |
-|----------------------------------------------------------------------------------|---------------------------------------------------------------|
-| [cmd/tictactoe](https://godoc.org/github.com/shurcooL/tictactoe/cmd/tictactoe)   | tictactoe plays a game of tic-tac-toe with two players.       |
-| [player/bad](https://godoc.org/github.com/shurcooL/tictactoe/player/bad)         | Package bad contains a bad tic-tac-toe player.                |
-| [player/human](https://godoc.org/github.com/shurcooL/tictactoe/player/human)     | Package human contains a human-controlled tic-tac-toe player. |
-| [player/perfect](https://godoc.org/github.com/shurcooL/tictactoe/player/perfect) | Package perfect implements a perfect tic-tac-toe player.      |
-| [player/random](https://godoc.org/github.com/shurcooL/tictactoe/player/random)   | Package random implements a random player of tic-tac-toe.     |
+| Path                                                                              | Synopsis                                                      |
+|-----------------------------------------------------------------------------------|---------------------------------------------------------------|
+| [cmd/tictactoe](https://pkg.go.dev/github.com/shurcooL/tictactoe/cmd/tictactoe)   | tictactoe plays a game of tic-tac-toe with two players.       |
+| [player/bad](https://pkg.go.dev/github.com/shurcooL/tictactoe/player/bad)         | Package bad contains a bad tic-tac-toe player.                |
+| [player/human](https://pkg.go.dev/github.com/shurcooL/tictactoe/player/human)     | Package human contains a human-controlled tic-tac-toe player. |
+| [player/perfect](https://pkg.go.dev/github.com/shurcooL/tictactoe/player/perfect) | Package perfect implements a perfect tic-tac-toe player.      |
+| [player/random](https://pkg.go.dev/github.com/shurcooL/tictactoe/player/random)   | Package random implements a random player of tic-tac-toe.     |
 
 License
 -------
 
--	[MIT License](https://opensource.org/licenses/mit-license.php)
+-	[MIT License](LICENSE)