Fix read-only instructions for running Beats on Docker (#41120) (#41149)

* Fix read-only instructions for running Beats on Docker

* Fix up command

(cherry picked from commit b7d7fec)

Co-authored-by: David Kilfoyle <41695641+kilfoyle@users.noreply.github.com>
Co-authored-by: Pierre HILBERT <pierre.hilbert@elastic.co>

libbeat/docs/shared-docker.asciidoc

@@ -149,9 +149,9 @@ For example:
 
 ["source", "sh", subs="attributes"]
 --------------------------------------------
-docker run \
-  --mount type=source=$(pwd}/data,destination=/usr/share/{beatname_lc}/data
-  --read-only
+docker run --rm \
+  --mount type=bind,source=$(pwd)/data,destination=/usr/share/{beatname_lc}/data \
+  --read-only \
   {dockerimage}
 --------------------------------------------