Content-wise, this shouldn't be significant:
1. clarify the intent of this document
2. clarify how to disable updates in the desktop app
3. reword the part about which extensions can access other websites to more accurately reflect reality
I had to update it because we will soon start caching TTS requests
through our server. I decided it would be best if we just finally
consolidated everything into one document instead of three (this one,
packager, and desktop) each cross-referencing eachother.
In terms of actual content updates, there shouldn't be much.
Changes static/favicon.ico to just favicon.ico. The job of finding the favicon is now left to the browser.
This is important if we want to give experiments its own favicon w/o modifying 40 branches