[btcsuite/btcutil] deba3d: Fix tiny typo in docs.

[Mawuli Adzoe]

  Branch: refs/heads/master
  Home:   https://github.com/btcsuite/btcutil
  Commit: deba3d64366b3ddb54460166d93b7529af70c977
      
https://github.com/btcsuite/btcutil/commit/deba3d64366b3ddb54460166d93b7529af70c977
  Author: Mawuli Adzoe <mawuli.kofi.maw...@gmail.com>
  Date:   2015-07-24 (Fri, 24 Jul 2015)

  Changed paths:
    M hdkeychain/example_test.go

  Log Message:
  -----------
  Fix tiny typo in docs.