Fixed spelling, grammar, and technical issues

I found a few other bugs, but need to file them separately... they are below. It explains why I removed some things, etc.. 

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# Basics

Basic concepts is wrong. 
The basic concepts section is not right. All web pages already have a name, and the ability to work offline. HTML also allows you to specify and icon (actually multiple icons, with `<link rel-icon` and using a favicon).

Also, there is no such thing as an open web app. Please refer to them as "hosted apps" or "packaged apps" where appropriate.  

The only different from a web page and a hosted app is the inclusion of a manifest. The manifest brings together metadata about the app in one convenient place. The other difference is that a hosted app might request access to some specific APIs up front. 

This statement is not true. "Keep in mind that there is a little overhead when launching the appcache enabled app because the system needs to check if the cache is up to date before launching the app."

This would violate Mozilla's distribution policies: "if you're distributing them on your own channel, you will need to create update routines in your app". 

This is a really bad reason to use a packaged app: "Personally, I'd rather build packaged apps because I don't like using appcache and dealing with web hosting servers for apps."

Access to Geolocation. 
You might need to confirm this:
"As we can see on the image above, any application can access the *Geolocation API* but only privileged apps can access the *WIFI Information API*."

I thought that in FxOS, geolocation access only available to privileged apps.

Add link to documentation page
where you say: 
"Lets review some code examples to see how easy those APIs are to use. Don't take this example as a full documentation of the WebAPI, they are just a small sample to make you understand how we can access device features using JavaScript."

You should add a link to where the actual documentation for APIs is.