add notes about usages

Author: etpinard

README.md

@@ -33,11 +33,15 @@ chart types, including 3D charts, statistical graphs, and SVG maps.
 git clone https://github.com/plotly/plotly.js.git
 ```
 
+and use the plotly.js `dist` file(s). More info [here](https://github.com/plotly/plotly.js/blob/master/dist/README.md).
+
 #### Install with `npm`
 ```bash
 npm install plotly.js
 ```
 
+and use the plotly.js `dist` or CommonJS files `var Plotly = require('plotly.js');` in your source file.
+
 #### Use the plotly.js CDN hosted by Fastly:
 ```html
 <!-- Latest compiled and minified plotly.js JavaScript -->
@@ -47,6 +51,8 @@ npm install plotly.js
 <script type="text/javascript" src="https://cdn.plot.ly/plotly-1.5.0.min.js"></script>
 ```
 
+and use the `Plotly` object in the window scope.
+
 Read the [Getting started page](https://plot.ly/javascript/getting-started/) for more examples.
 
 ## Modules