Update 06-android-app.html.md

I added a little more information about the preferences tab (on my galaxy s3 I accessed it from the bottom menu button, it was nowhere to be found at the top).  And, there was no reference that something had to be filled in under "collection" in the preferences menu of the app on the phone, so I didn't do it the first time around.  I was following the directions to the letter, so I think it should be mentioned.