Removed a println

readme.md

@@ -30,7 +30,8 @@ and field line tracing:
 
 ## To Use
 
-For now, here is a simple example of using the propagator to solve a simple system:
+For now, here is a simple example of using the propagator to solve a simple second-order system (the
+pendulum problem):
 
 ```rust
 use nalgebra::Vector2;