Added more definition on the Good Parts and another link on Portal secti...

Added more definitions on the Good Parts and another link on Portal section.

In the Good Parts added:
- Closure Function (source: Mozilla Developer Network (MDN) and my overview text from source)
- IIFE (source: Mozilla Developer Network (MDN))
- Use Strict  (source: @cowboy page and my adapted text from source)

In the section Portal added:
- HTML5Rocks