These have been replaced by the initial stream messages and PMs.
The two pieces of information that exist here and not in the initial stream
messages are a link to /integrations, and a demonstration of image
uploading/pasting.
I think the current information presented is already a lot, though probably
it would be good to work in integrations somehow. Image pasting should just
be done in a separate Zulip that demonstrates the many different formatting
features.
This link was broken when we hardened the access model for user file
uploads to not work cross-realm. The right solution is just to
include the image in the codebase so it's guaranteed to exist.
Fixes#205.