v0.1.11 Add Bratu example
add test example: Bratu problem with contique
by using the finite-differences approach (https://www.sciencedirect.com/science/article/pii/S089812211300610X).
add test example: Bratu problem with contique
by using the finite-differences approach (https://www.sciencedirect.com/science/article/pii/S089812211300610X).