[btcsuite/btcd] 6e133b: txscript: Fix docs to match function.

[Mawuli Adzoe]

  Branch: refs/heads/master
  Home:   https://github.com/btcsuite/btcd
  Commit: 6e133b58daa9f424cc3ba9a1a9b1cfd2eb129e75
      
https://github.com/btcsuite/btcd/commit/6e133b58daa9f424cc3ba9a1a9b1cfd2eb129e75
  Author: Mawuli Adzoe <mawuli.kofi.maw...@gmail.com>
  Date:   2015-12-29 (Tue, 29 Dec 2015)

  Changed paths:
    M txscript/sigcache_test.go

  Log Message:
  -----------
  txscript: Fix docs to match function.

Changed the order of return values described in the docs to be
consistent with the function’s actual return value signature.