Some change proposals for index.tex

Something that caught my eye.
Also, just to point out:
+ not sure about mentioning other Erlang projects, like N2O, cowboy, etc, maybe, need to add links
+ 'that fits out Web Stack' - couldn't get the actual meaning behind that
+ 'mad packages priv directories' - same as previous one
+ './web_app' under Windows might be throwing an error because or the wrong delimiter