Remove outdated remark about take(n).

Looking at the code, I believe this remark about `take(n)` computing partitions on the driver is no longer correct. Apologies if I'm wrong.

This came up in http://stackoverflow.com/q/28436559/3318517.

Author: Daniel Darabos <darabos.daniel@gmail.com>

Closes #4533 from darabos/patch-2 and squashes the following commits:

cc80f3a [Daniel Darabos] Remove outdated remark about take(n).

docs/programming-guide.md

@@ -975,7 +975,7 @@ for details.
 </tr>
 <tr>
   <td> <b>take</b>(<i>n</i>) </td>
-  <td> Return an array with the first <i>n</i> elements of the dataset. Note that this is currently not executed in parallel. Instead, the driver program computes all the elements. </td>
+  <td> Return an array with the first <i>n</i> elements of the dataset. </td>
 </tr>
 <tr>
   <td> <b>takeSample</b>(<i>withReplacement</i>, <i>num</i>, [<i>seed</i>]) </td>