Fix document about defer file operation

doc/deferredFileOperations.md

@@ -12,6 +12,13 @@ To perform file operations, write a text file (in the UTF-8 encoding) at `myapp.
 
 The success or failure of these operations will be recorded in the event log.
 
+`src` and `dst` should be the full path to file, or you will see failed to copy file.
+
+example:
+
+```
+c:\soft\sshd.exe.new>c:\bin\ssh.exe
+```
 Note that it is apparently possible to [rename executables even when it's running](http://superuser.com/questions/488127/why-can-i-rename-a-running-executable-but-not-delete-it), which makes sense if you think about file handles.
 Kohsuke has failed to find any authoritative source of information about this, but experimentally this even works on Windows XP and presumably on all the later Windows versions. 
 This behavior can be used to update `winsw.exe` itself.