Created Contributing.md file

Author: Brian Jimenez

Diff for: CONTRIBUTING.md

@@ -0,0 +1,18 @@
+# How to contribute
+
+Contributing to this project is more than welcome. The easiest way is to write your custom scoring functions and pull them for request.
+
+## Custom scoring functions
+
+You can write your own scoring function starting from the provided [driver.py](lightdock/scoring/template/driver.py) template.
+The easiest way is to copy the template folder:
+
+```
+cp -R template/ mynewscoring
+```
+
+In order to call this new scoring function, just use the ```-s``` flag:
+
+```
+lightdock 2UUY_rec.pdb 2UUY_lig.pdb 1 10 5 -s mynewscoring
+```