install: Resupport Ubuntu 22.04.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

docs/development/setup-advanced.md

@@ -12,7 +12,7 @@ Contents:
 If you'd like to install a Zulip development environment on a computer
 that's running one of:
 
-- Ubuntu 20.04
+- Ubuntu 20.04, 22.04
 - Debian 11
 - CentOS 7 (beta)
 - Fedora 33 and 34 (beta)

docs/development/setup-vagrant.md

@@ -49,7 +49,7 @@ a proxy to access the internet.)
 
 - **All**: 2GB available RAM, Active broadband internet connection, [GitHub account][set-up-git].
 - **macOS**: macOS (10.11 El Capitan or newer recommended)
-- **Ubuntu LTS**: 20.04
+- **Ubuntu LTS**: 20.04 or 22.04
 - **Debian**: 11
 - **Windows**: Windows 64-bit (Win 10 recommended), hardware
   virtualization enabled (VT-x or AMD-V), administrator access.

docs/production/requirements.md

@@ -5,6 +5,7 @@ To run a Zulip server, you will need:
 - A dedicated machine or VM
 - A supported OS:
   - Ubuntu 20.04
+  - Ubuntu 22.04
   - Debian 11
 - At least 2 GB RAM, and 10 GB disk space
   - If you expect 100+ users: 4 GB RAM, and 2 CPUs
@@ -32,7 +33,7 @@ on issues you'll encounter](install-existing-server.md).
 
 #### Operating system
 
-Ubuntu 20.04 and Debian 11
+Ubuntu 20.04, Ubuntu 22.04, and Debian 11
 are supported for running Zulip in production. You can also
 run Zulip on other platforms that support Docker using
 [docker-zulip][docker-zulip-homepage].