[btcsuite/btcd] ff0c78: Fix inconsistent spacing.

[Mawueli Kofi Adzoe]

  Branch: refs/heads/master
  Home:   https://github.com/btcsuite/btcd
  Commit: ff0c78723714df9ca472159cef66bfa2849b5831
      
https://github.com/btcsuite/btcd/commit/ff0c78723714df9ca472159cef66bfa2849b5831
  Author: Mawueli Kofi Adzoe <wallclockbuil...@googlemail.com>
  Date:   2015-12-29 (Tue, 29 Dec 2015)

  Changed paths:
    M docs/code_contribution_guidelines.md

  Log Message:
  -----------
  Fix inconsistent spacing.

 guidelinestherin ---> guidelines therein.