Fixed error in heading.

README.md

 # Research Computing Summer School: Introduction to Medical Image Computing
 
-####Friday 27th September 2019
+#### Friday 27th September 2019
 
 Welcome to the **Introduction to Medical Image Computing Tutorial** being held as part of the [Imperial Research Computing Summer School 2019](http://www.imperial.ac.uk/computational-methods/news-and-events/hpc-2019/).
 
@@ -104,4 +104,4 @@ $ source /vol/lab/course/416/venv/bin/activate
 
 ##### Starting the tutorial
 
-Begin the tutorial by opening the first notebook - `1-Medical-Image-Computing.ipynb`
\ No newline at end of file
+Begin the tutorial by opening the first notebook - `1-Medical-Image-Computing.ipynb`