Updated text visible to logged out users on welcome page

Provided a simple explanation of the main features included in PAT-FB. (My HTML is about ten years old, so hopefully I coded it right.) 

Also changed language to suggest talking to a friend (e.g. "Share your story") rather than interacting with law enforcement (e.g. "File a report"). Might be a good idea to change language inside the app in a similar way.

It took me a few tries to get this right. Sorry the commits are a little messy.