We recently changed /developer-community to /development-community.
Now that this change is in production, we can also migrate the
external links in our ReadTheDocs documentation.
We're migrating to using the cleaner zulip.com domain, which involves
changing all of our links from ReadTheDocs and other places to point
to the cleaner URL.
This provides a nice user experience for folks where we do know what
their LDAP credentials are.
Though we need to fix#10917 before the content in the email with be
correct.
I think an hour after signup is not the right time to try to get someone to
re-engage with a product.
This also makes the day1 email clearly a transactional email both in
experiencing the product and in the eyes of various anti-spam laws, and
allows us to remove the unsubscribe link.