[CI:DOCS] rootless_tutorial: Remove incorrect advice regarding volume…

…s and mount points

* Remove the instruction
  "The mount point must exist in the container"
  as it is incorrect which is shown by this example
  ```
  $ mkdir dir1
  $ podman run --rm -v ./dir1:/dir1:Z docker.io/library/fedora:36 touch /dir1/file
  $ ls dir1
  file
  $ podman run --rm docker.io/library/fedora:36 ls -l /dir1
  ls: cannot access '/dir1': No such file or directory
  $ podman --version
  podman version 4.1.1
  $
  ```

* Rewrite the advice "You should always give the full path to the volume you'd like to mount"
  so that it also mentions relative paths starting with a dot.

Signed-off-by: Erik Sjölund <[email protected]>

docs/tutorials/rootless_tutorial.md

@@ -186,10 +186,10 @@ We do recognize that this doesn't really match how many people intend to use roo
 
 It is also helpful to distinguish between running Podman as a rootless user, and a container which is built to run rootless. If the container you're trying to run has a `USER` which is not root, then when mounting volumes you **must** use `--userns=keep-id`. This is because the container user would not be able to become `root` and access the mounted volumes.
 
-Other considerations in regards to volumes:
+Another consideration in regards to volumes:
 
-- You should always give the full path to the volume you'd like to mount
-- The mount point must exist in the container
+- When providing the path of a directory you'd like to bind-mount, the path needs to be provided as an absolute path
+  or a relative path that starts with `.` (a dot), otherwise the string will be interpreted as the name of a named volume.
 
 ## More information