[gmx-users] water tutorial

[chris.neale at utoronto.ca]

Just change the numbers at the bottom of the new file to match the old values.

As far as I can tell, there is no way to tell pdb2gmx or editconf to respect pbc
and the result is that the box size expands or else molecules are removed. This
is not so much of a problem for water boxes, but it can be a real pain when
trying to convert a membrane from -ur rect to -ur dodecahedron (anyone know how
to do that?)