doc: correct "or" to "and" in MountFlags= description (systemd#5010)

Author: ian-kelling

man/systemd.exec.xml

@@ -1179,7 +1179,7 @@
 
         <listitem><para>Takes a mount propagation flag: <option>shared</option>, <option>slave</option> or
         <option>private</option>, which control whether mounts in the file system namespace set up for this unit's
-        processes will receive or propagate mounts or unmounts. See <citerefentry
+        processes will receive or propagate mounts and unmounts. See <citerefentry
         project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
         details. Defaults to <option>shared</option>. Use <option>shared</option> to ensure that mounts and unmounts
         are propagated from the host to the container and vice versa. Use <option>slave</option> to run processes so