Update tutorial-double-integrator-energy.md

Author: ocots

docs/src/tutorial-double-integrator-energy.md

@@ -1,4 +1,4 @@
-# [Double integrator: energy min](@id tutorial-double-integrator-energy)
+# [Double integrator: energy minimisation](@id tutorial-double-integrator-energy)
 
 Let us consider a wagon moving along a rail, whom acceleration can be controlled by a force $u$.
 We denote by $x = (x_1, x_2)$ the state of the wagon, that is its position $x_1$ and its velocity $x_2$.
@@ -137,4 +137,4 @@ sol_json = import_ocp_solution(ocp; filename_prefix="my_solution", format=:JSON)
 
 println("Objective from computed solution: ", objective(sol))
 println("Objective from imported solution: ", objective(sol_json))
-```
+```