Correct the dump-load format documentation: the revprops section is optional.
Correct the dump-load format documentation: the revprops section is
optional.

* notes/dump-load-format.txt
  Correct the assertion that a Revision record must have a properties
  section. While svnadmin always writes a properties section even if there
  are no revprops, svndumpfilter omits the properties section in that case.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1652064 13f79535-47bb-0310-9956-ffa450edef68

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