List CSP/Proxy requirements for the extension

[clarkwinkelmann]

We need to provide the users with a list of resources they must authorize access to so bazaar can work in their environment. For instance (may be incomplete):

Server-side: (if using a proxy)

• Allow HTTPS access to flagrow.io

Client-side: (if using CSP)

• Allow HTTPS images from flagrow.io

[luceos]

This should probably go into the documentation/readme/faq?