On the 'move-tracking-2' branch: Update a doc string following r1707086.
On the 'move-tracking-2' branch: Update a doc string following r1707086.

* subversion/include/private/svn_branch.h
  (svn_branch_get_element): Update the doc string.

git-svn-id: 486ec3464084f62cfe8608152673c827b947faa2@1708573 13f79535-47bb-0310-9956-ffa450edef68

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