Improve wording in help text of 'svn copy' and 'svn move'.
Improve wording in help text of 'svn copy' and 'svn move'.

* subversion/svn/svn.c
  (svn_cl__cmd_table): Explain more clearly what happens when
   copying/moving multiple sources. Explicitly state that the
   destination must be an existing directory in this case.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1780921 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion