README: convert to Markdown, as pkg.go.dev doesn't play well with org-mode

Author: dnaeon

README.md

@@ -0,0 +1,28 @@
+# go-binarytree
+
+A simple implementation of [Binary Trees](https://en.wikipedia.org/wiki/Binary_tree) in Go.
+
+## Installation
+
+Install `go-binarytree` by executing the following command.
+
+``` shell
+go get -v gopkg.in/dnaeon/go-binarytree.v1
+```
+
+## Usage
+
+See the included [test cases](./binarytree_test.go) for some examples.
+
+## Tests
+
+Run the tests.
+
+``` shell
+make test
+```
+
+## License
+
+`go-binarytree` is Open Source and licensed under the [BSD
+License](http://opensource.org/licenses/BSD-2-Clause).