rootles tutorial: remove systemd unit example

The example was not entirely correct.  Users should use `podman generate
systemd` and use the output either directly or as a template for further
adjustments to their needs.  Keeping an example in the rootless tutorial
is a maintenance burdon and can easily suggest incorrect usage patterns
to users.

Signed-off-by: Valentin Rothberg <[email protected]>

Author: vrothberg

docs/tutorials/rootless_tutorial.md

@@ -110,34 +110,6 @@ The Podman configuration files for root reside in `/usr/share/containers` with o
 
 The default authorization file used by the `podman login` and `podman logout` commands reside in `${XDG_RUNTIME_DIR}/containers/auth.json`.
 
-## Systemd unit for rootless container
-
-```
-[Unit]
-Description=nginx
-[email protected]
-[email protected]
-[Service]
-Type=simple
-KillMode=none
-MemoryMax=200M
-ExecStartPre=-/usr/bin/podman rm -f nginx
-ExecStartPre=/usr/bin/podman pull nginx
-ExecStart=/usr/bin/podman run --name=nginx -p 8080:80 -v /home/nginx/html:/usr/share/nginx/html:Z nginx
-ExecStop=/usr/bin/podman stop nginx
-Restart=always
-User=nginx
-Group=nginx
-[Install]
-WantedBy=multi-user.target
-```
-
-This example unit will launch a nginx container using the existing user nginx with id 1001, serving static content from /home/nginx/html and limited to 200MB of RAM.
-
-You can use all the usual systemd flags to control the process, including capabilities and cgroup directives to limit memory or CPU.
-
-See #3866 for more details.
-
 ## More information
 
 If you are still experiencing problems running Podman in a rootless environment, please refer to the [Shortcomings of Rootless Podman](https://github.com/containers/libpod/blob/master/rootless.md) page which lists known issues and solutions to known issues in this environment.