Doc fixes --- give a general overview of how trails and svn_fs__retry_txn are supposed to be used.
Doc fixes --- give a general overview of how trails and
svn_fs__retry_txn are supposed to be used.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@838747 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion