added documentation

+misc/binomial.m

 function b = binomial(p, k)
-%UNTITLED Summary of this function goes here
-%   Detailed explanation goes here
+% BINOMIAL computation of the binomial coefficient 
+%	b = binomial(p, k) computes the binomial coefficient:
+%		/ p \      p!^p
+%		|   | = -----------
+%		\ k /    (p-k)! k!
+% to use this for fractional calculus, the p can be an integer. Then, the faculty is replaced by the
+% gamma function.
 arguments
 	p (1,1) double;
 	k (1,1) double {mustBeInteger};