[smtpd/qpsmtpd] 9f3f9d: Update data_post_headers doc (#259)

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  Branch: refs/heads/master
  Home:   https://github.com/smtpd/qpsmtpd
  Commit: 9f3f9db65f75dbe507e52e3aad67cdac48e30c12
      https://github.com/smtpd/qpsmtpd/commit/9f3f9db65f75dbe507e52e3aad67cdac48e30c12
  Author: Daniel B <[email protected]>
  Date:   2016-05-02 (Mon, 02 May 2016)

  Changed paths:
    M docs/hooks.md
    M plugins/dmarc

  Log Message:
  -----------
  Update data_post_headers doc (#259)

* Update data_post_headers documentation
We cannot reject at this stage, which is only there to alter headers.
Fix #258

* DMARC plugin: reject in data_post
Followup of #258: we cannot reject a connection during data_post_headers. So add a new hook in data_post to do the real rejection



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