[btcsuite/btcd] 88b15e: docs: Add info describing model commit messages.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/btcsuite/btcd
  Commit: 88b15e74f0a1373c621c314d7b5db59323194c48
      
https://github.com/btcsuite/btcd/commit/88b15e74f0a1373c621c314d7b5db59323194c48
  Author: Dave Collins <da...@conformal.com>
  Date:   2015-07-30 (Thu, 30 Jul 2015)

  Changed paths:
    M docs/code_contribution_guidelines.md

  Log Message:
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  docs: Add info describing model commit messages.