Add readme

Author: Philipp Alferov

readme.md

@@ -0,0 +1,51 @@
+# array-to-tree
+
+> Convert a plain array of nodes (with pointers to parent nodes) to a tree.
+
+Solves a problem with conversion of retrieved from a database sets of data to a nested structure (i.e. navigation tree).
+
+## Install
+
+```
+$ npm install --save array-to-tree
+```
+
+## Usage
+
+```js
+var arrayToTree = require('array-to-tree');
+
+var navigation = [{
+  id: 1,
+  name: "Portfolio",
+  parent_id: null
+}, {
+  id: 2,
+  name: "Web Development",
+  parent_id: 1
+}, {
+  id: 3,
+  name: "Recent Works",
+  parent_id: 2
+}, {
+  id: 4,
+  name: "About Me",
+  parent_id: null
+}];
+
+var navigationTree = arrayToTree(navigation);
+
+/*
+ * Output:
+ * Portfolio
+ *   Web Development
+ *     Recent Works
+ * About Me
+ */
+
+```
+
+## License
+
+MIT
+[Philipp Alferov](https://github.com/alferov)