Incomplete docs

[Jake Kesinger]

I'm a brand new user of GSL (where was this when I *really* needed it
three years ago? :-)  and I notices that the docs could use a little bit 
of sprucing up, especially with some of the special functions (i.e.
Gamma(z), and Legendre polynomials).  

I *am* volunteering to try and add a little verbiage to the docs, if
the maintainers are interested.  Please let me know.

  ==Jake