docs(readme): add installation section

README.md

@@ -2,6 +2,19 @@
 
 An alternative library for interacting with vk.com with solid and exceptionally convenient API.
 
+## Install
+
+The driver is packaged as an [UMD](https://github.com/umdjs/umd) and is published to:
+
+- [NPM](https://www.npmjs.com/package/@vk-x/vk-api): `npm install --save @vk-x/vk-api`
+- [Bower](http://bower.io/search/?q=vk-api): `bower install vk-api`
+- [jsDelivr CDN](http://www.jsdelivr.com/projects/vk-api): `https://cdn.jsdelivr.net/vk-api/latest/vk-api.min.js`
+- A smaller version without method shortcuts is also available: `https://cdn.jsdelivr.net/vk-api/latest/vk-api-no-shortcuts.min.js`
+
+## Use
+
+After you've included and loaded the script, you can use it either with Promises or with callbacks.
+
 ```JavaScript
 
 // Authenticate on your website.