[Checkins] [zopefoundation/z3c.relationfield] d09ace: better documentation of new feature

[Jens W. Klein]

  Branch: refs/heads/configurable-indexes
  Home:   https://github.com/zopefoundation/z3c.relationfield
  Commit: d09ace3f13082a3cff9752087ebaf08d280127e6
      https://github.com/zopefoundation/z3c.relationfield/commit/d09ace3f13082a3cff9752087ebaf08d280127e6
  Author: Jens W. Klein <jk at kleinundpartner.at>
  Date:   2019-02-08 (Fri, 08 Feb 2019)

  Changed paths:
    M CHANGES.rst
    M src/z3c/relationfield/README.rst
    M src/z3c/relationfield/index.py

  Log Message:
  -----------
  better documentation of new feature