fix a typo.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@19219 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

array.c

@@ -3012,7 +3012,7 @@ rb_ary_shuffle(VALUE ary)
  *     array.sample        -> obj
  *     array.sample(n)     -> an_array
  *  
- *  Choose a random element, or the random +n+ elements, fron the array.
+ *  Choose a random element, or the random +n+ elements, from the array.
  *  If the array is empty, the first form returns <code>nil</code>, and the
  *  second form returns an empty array.
  *