Change Delivery section title in the French check-out page

[Antoine123]

Hi all!

I am trying to rename the delivery section title of my French check-out page. This is currently named "Livraison" (Delivery in French) which is misleading as we offer only self-collect option. Thus I would like to rename it into "Retrait" (Self pick-up).

I went through all the Theme language content but could not find anything. 

Any idea how to do?

Thanks!

Antoine