Add colour lib reference

README.md

@@ -5,10 +5,11 @@ From https://github.com/gdiepen/face-recognition / track multiple faces
 Project to be shown in Marseille on the 30th of january, 2020, for the Technopolice project.
 
 INSTALLATION:
-Need opencv, opencv-contrib, dlib
+Need opencv, opencv-contrib, dlib, colour
 
 ```
 pip install opencv-python
 pip install opencv-contrib-python
 pip install dlib
+pip install colour
 ```