message: Update README.md
  I added 3 more usage sections.
diff: @@ -96,6 +96,22 @@ To perform whole protein docking:
  gnina -r rec.pdb -l lig.sdf --autobox_ligand rec.pdb -o whole_docked.sdf.gz --exhaustiveness 64
  ```
  +To utilize the default enemble CNN in the energy minimization during the refinement step of docking (10 times slower than the default rescore option):
  +```
  +gnina -r rec.pdb -l lig.sdf --autobox_ligand orig.sdf --cnn_scoring refinement -o cnn_refined.sdf.gz
  +```
  +
  +To utilize the default enemble CNN for every step of docking (100 times slower than the default rescore option):
  +```
  +gnina -r rec.pdb -l lig.sdf --autobox_ligand orig.sdf --cnn_scoring all -o cnn_all.sdf.gz
  +```
  +
  +To utilize a different CNN during docking (see help for possible options):
  +```
  +
  +gnina -r rec.pdb -l lig.sdf --autobox_ligand orig.sdf --cnn dense -o dense_docked.sdf.gz
  +```
  +
  To minimize and score ligands `ligs.sdf` already positioned in a binding site:
  ```
  gnina -r rec.pdb -l ligs.sdf --minimize -o minimized.sdf.gz
  