Update the list of Debian releases that work out of the box

It is still possible to create containers for jessie and stretch, although you
need to manually specify the archive mirror and keyring:

    lxc-create -t debian -n stretch -- -r stretch \
      --mirror=http://archive.debian.org/debian \
      --keyring=/usr/share/keyrings/debian-archive-removed-keys.gpg

While the jessie container starts up, it doesn't automatically get an IP -- I
didn't perform any further investigation. stretch works just fine.

Debian releases wheezy and earlier fail to create the container in various ways.

This commit just changes the presented list of releases; there is some existing
logic for handling archived releases, but I didn't want to risk breaking things
by tinkering with the existing code.

Signed-off-by: Mathias Gibbens <gibmat@debian.org>

templates/lxc-debian.in

@@ -691,8 +691,8 @@ Options :
   -S, --auth-key=KEYFILE SSH public key to inject into the container as the root user.
   -a, --arch=ARCH        The container architecture. Can be one of: i686, x86_64,
                          amd64, armhf, armel, powerpc. Defaults to host arch.
-  -r, --release=RELEASE  Debian release. Can be one of: wheezy, jessie, stretch, buster,
-                         bullseye, bookworm, trixie, sid. Defaults to current stable.
+  -r, --release=RELEASE  Debian release. Can be one of: buster, bullseye, bookworm, trixie,
+                         testing, sid. Defaults to current stable.
   --mirror=MIRROR        Debian mirror to use during installation. Overrides the MIRROR
                          environment variable (see below).
   --keyring=KEYRING      GPG keyring to authenticate the repository against.