Turn sentence in to section header.

Author: drvinceknight

README.md

@@ -3,7 +3,7 @@
 - Aimed at Mathematicians with little to no Python knowledge.
 - All documents are written as [Jupyter notebooks](./nbs/).
 
-Topics covered:
+## Topics covered:
 
 1. [Basic Python](./nbs/00 - Studying Mathematics with Python.ipynb)
 2. [Using Sympy](./nbs/01 - Symbolic mathematics with Sympy.ipynb) for symbolic