message: Fix Sierra typo
diff: # OutpostHD Readme
  -OutpostHD is a reimplementation of OUTPOST published by Siera On-Line in 1994. It is not a clone. It's a complete redesign of OUTPOST taking the core concepts and reimplementing them in a much more fun and more responsive game.
  +OutpostHD is a reimplementation of OUTPOST published by Sierra On-Line in 1994. It is not a clone. It's a complete redesign of OUTPOST taking the core concepts and reimplementing them in a much more fun and more responsive game.
  For up to the minute information, please visit The Outpost Universe's [online forum](http://forum.outpost2.net). You may also view [OutpostHD's Forum Thread](http://forum.outpost2.net/index.php/topic,5718.0.html) for additional details or to participate in the discussion.
  