man: tone down claims on processes having exited already in ExecStop=

Processes can easily survive the first kill operation we execute, hence
we shouldn't make strong claims about them having exited already. Let's
just say "likely" hence.

Fixes: #15032
(cherry picked from commit ac804bc)
(cherry picked from commit 307a633)
(cherry picked from commit b38386a)
(cherry picked from commit e23cbec)
(cherry picked from commit 3ddb795)

Author: poettering

man/systemd.service.xml

@@ -570,11 +570,11 @@
         <varname>ExecStop=</varname> – commands specified with this setting are invoked when a service failed to start
         up correctly and is shut down again.</para>
 
-        <para>It is recommended to use this setting for clean-up operations that shall be executed even when the
-        service failed to start up correctly. Commands configured with this setting need to be able to operate even if
-        the service failed starting up half-way and left incompletely initialized data around. As the service's
-        processes have been terminated already when the commands specified with this setting are executed they should
-        not attempt to communicate with them.</para>
+        <para>It is recommended to use this setting for clean-up operations that shall be executed even when
+        the service failed to start up correctly. Commands configured with this setting need to be able to
+        operate even if the service failed starting up half-way and left incompletely initialized data
+        around. As the service's processes have likely exited already when the commands specified with this
+        setting are executed they should not attempt to communicate with them.</para>
 
         <para>Note that all commands that are configured with this setting are invoked with the result code of the
         service, as well as the main process' exit code and status, set in the <varname>$SERVICE_RESULT</varname>,