Update some tree-conflicts design notes.
Update some tree-conflicts design notes.

* notes/tree-conflicts/design-overview.txt
  Reflect that APIs for getting the textual description of a conflict have
  been moved to a higher level.
  Combine the "resolving" and "resolved" sections into one.
  Some other updates.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@871777 13f79535-47bb-0310-9956-ffa450edef68

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