Space Law book link fix

Fixed the link in the Space Law book to correctly link to the printable
version of the space law page on the wiki.  Note that it uses Space_law
and not Space_Law on the wiki, as the font is smaller, but there are
some formatting errors on that page.  I can't edit the wiki page
directly to fix this because it's protected, but I wanted to keep the
smaller font to make it easier to read in game.

My first patch of many hopefully, and thanks to UC_guy for helping me get to grips with github.