recommend fuse-overlayfs for Debian too

Debian kernel has a non-upstream modprobe option `permit_mounts_in_userns=1`
for kernel-mode overlayfs, but seems unstable: moby/moby issue 42302

So we should recommend fuse-overlayfs for Debian (until the release of
Debian 12, which will support genuine kernel-mode overlayfs with kernel
>= 5.11).

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

deb/common/control

@@ -92,9 +92,9 @@ Conflicts: rootlesskit
 Replaces: rootlesskit
 Breaks: rootlesskit
 # slirp4netns (>= 0.4.0) is available in Debian since 11 and Ubuntu since 19.10
-Recommends: slirp4netns (>= 0.4.0)
-# Unlike RPM, DEB packages do not contain "Recommends: fuse-overlayfs (>= 0.7.0)" here,
-# because Debian (since 10) and Ubuntu support the kernel-mode rootless overlayfs.
+# fuse-overlayfs is recommended for Debian 10 and 11 (kernel < 5.11). Not needed for Ubuntu.
+Recommends: slirp4netns (>= 0.4.0),
+            fuse-overlayfs (>= 0.7.0)
 Description: Rootless support for Docker.
   Use dockerd-rootless.sh to run the daemon.
   Use dockerd-rootless-setuptool.sh to setup systemd for dockerd-rootless.sh .