Fix doc string typos.

* subversion/include/svn_fs.h
  (svn_fs_lock2, svn_fs_unlock2): Fix typos.

* subversion/include/svn_repos.h
  (svn_repos_fs_lock2, svn_repos_fs_unlock2, svn_repos_fs_unlock):
    Fix typos and Doxygen mark-up.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1583630 13f79535-47bb-0310-9956-ffa450edef68