Update README.md

README.md

-#pymolfile
+# pymolfile
 
 Usage example:
 
+```python
 import pymolfile
 
 molfile = pymolfile.OpenMolfile('test/ala3.pdb')
@@ -11,4 +12,5 @@ print(molfile.topology.bonds)
 print(molfile.topology.angles)
 
 molfile_traj = molfile.trajectory.iread()
+```