fairland: Add a comment describing how fairland works

fairland: Add a comment describing how fairland works

A comment describing how fairland works was lost some time after
Chainsaw 3.31.  This is the last known version:

    The algorithm starts out by placing the "capitols" on the torus in
    such a way so as to maximize their distances from one another (this
    uses the perterbation technique of calculus of variations).  Then from
    these seeds, the continents are grown.  The kind of shape they grow
    into is determined by the "spike" argument <sp>--the higher the spike,
    the more spindly they will be.  If you lower the spike, the continents
    will be more round.  The continents never touch one another, the
    argument <di> specifies how many sectors of water should be between
    the continents at all times.  The continents grow to the size you
    specify with <sc> and they all get the same number of mountains
    (specified by <pm>).  The other arguments should be self explanitory.
    If #define ORE 1, then resources will be placed in the sectors as well.
    You can alter the #define ORE_MAX, IRON_MIN, GOLD_MIN, FERT_MAX and
    URAN_MIN to affect what kind of resources the world gets.

It leaves much to be desired.  Add a more thorough one.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>