Improve the instructions for the 'hello world' example

examples/helloworld/README.md

@@ -1,10 +1,16 @@
-## "Hello World" overview
+## Overview
 
-This example is a minimalistic application of the PDF.js project. The file
-`helloworld.pdf` originates from the GNUpdf project and contains a simple and
-human-readable PDF.
+The "hello world" example is a minimalistic application of the PDF.js project.
+The file `helloworld.pdf` originates from the GNUpdf project and contains a
+simple and human-readable PDF.
 
 ## Getting started
 
-Point your browser to `index.html`. Voila. Take a peek at `hello.js` to see
-how to make basic calls to `pdf.js`.
+Instead of simply opening `index.html` in a browser, you must serve the page
+using a web server. This can be done on your local machine without an internet
+connection. In the root directory of PDF.js, run `node make server` in a
+terminal. The example can then be viewed using the following URL:
+
+`http://localhost:8888/examples/helloworld/index.html`
+
+Take a look at `hello.js` to see how to make basic calls to PDF.js.