adapt training slides to new theme

2019/2019-06-11_gitTraining/slides/whyCare.md

-## Why you should care (1)
+# Why you should care (1)
 
 <div align="center">
 <video width="40%" controls>
@@ -18,7 +18,7 @@ Ariane 5 launched with the same software as Ariane 4 - **the code had not been t
 
 
 
-## Why you should care (2)
+# Why you should care (2)
 
 <div align="center">
 <img src="slides/img/therac.png">