contourc.m documentation

[John W. Eaton]

On 14-Feb-2008, Olaf Till wrote:

| Octave-3.0, contourc.m, documentation text:
| 
| "If X and Y are omitted they are taken as the row/column index of Z."
| 
| Should probably be "column/row" index instead. Maybe a line stating
| whether rows or columns of Z are corresponding to X and Y,
| respectively, would also be useful.

Please suggest specific rewording.

jwe