[conformal/btcd] 22600c: Correct a couple of usage inconsistencies.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcd
  Commit: 22600c7c676bac43e0186df102502d52ea8f5d6f
      
https://github.com/conformal/btcd/commit/22600c7c676bac43e0186df102502d52ea8f5d6f
  Author: Dave Collins <da...@conformal.com>
  Date:   2013-11-19 (Tue, 19 Nov 2013)

  Changed paths:
    M config.go

  Log Message:
  -----------
  Correct a couple of usage inconsistencies.

- Remove periods from --rpccert/--rpckey since none of the other options use
  them
- Make it a little more clear that the --listen and --rpclisten options can be
  used multiple times by changing the summary to start with "Add an ..."
  which also matches the --addpeer style