getting coordinate file based on info in final output README.md

[jesperswillem]

For option:
"""""

• You may want to get a pdb file of your last frame. You can first
  check the total time of your trajectory and then use this time to
  request the last frame with:

echo 1 | gmx trjconv -b 5000 -e 5000 -f traj_pymol.xtc -o last51.pdb
"""

This only works if you also have generated a .tpr file, like such:
gmx grompp -f eqCA.mdp -c confout.gro -p prod.top -o topol.tpr -maxwarn 5