[Freeciv-Dev] more freeciv manual corrections

[Greg Wooledge <ic5035%tss1crs.amgreetings.com@xxxxxxxxxxxxxxxxxxxx>]

Most of these are just typos, of course.

game-12.html:
  "storage is empties" -> "storage is emptied"

  Rapture has differing effects based on government type.  The
    explosive growth is only for Republic/Democracy.  (This should be
    added to the helpdata.txt as well -- I think it's a rather recent
    addition to Freeciv.)

game-13.html:
  "a city's centered is" -> "a city's center is"

game-14.html:
  "enough slots as" -> "as many slots as"

  "building unit another" -> "building another unit"

  "Engineers" -> "Engineer"

game-15.html:
  "nations'" -> "nation's"

  "gold taxes, If" -> "gold taxes.  If"

game-16.html:
  Statue of Liberty also "eliminates" the period of Anarchy when switching
    governments.  (Without Fundamentalism in the game, this is the more
    important of the two effects.)

game-17.html:
  "them Every" -> "them.  Every"

  Mention that when a trade route is established, the player gets some gold
    immediately.

game-18.html:
  Warrior production cost is 10, not 18.

game-20.html:
  "You may with" -> "You may win"

game-21.html:
  Much of the difference between Freeciv and Civ2 is not due to a reduction
    of Civ2's features; rather, it's because Freeciv was originally based
    on Civ1, and so not all of Civ2's improvements have been added yet.
    (Of course, some have been omitted intentionally.)

Still more diffs between Freeciv and Civ2:
  Nuclear units require only Rocketry, not Rocketry + Nuclear Fission.
    (I don't think that's in the Civ2 docs; it sure caught *me* by
    surprise!)

  Automatic partisan generation uses more strict rules.  (Civ2 does not
    require the player to be the original city founder; there may be
    other differences as well.)

  The Trireme's chance of being lost at sea is a flat 50%, not modified by
    Navigation and other advances.

  Veteran Spies and Diplomats aren't handled properly (yet?).