fix(02_Dependent_Type_Theory): typo
fix(02_Dependent_Type_Theory): typo

cjmazey/fork_leanprover_tutorial,cjmazey/fork_leanprover_tutorial,fpvandoorn/tutorial,Hodapp87/cs6460_project,leanprover/tutorial,leanprover/tutorial,fpvandoorn/tutorial,soonhokong/lean-tutorial,soonhokong/lean-tutorial,cjmazey/fork_leanprover_tutorial,leanprover/tutorial,Hodapp87/cs6460_project,Hodapp87/cs6460_project,fpvandoorn/tutorial,soonhokong/lean-tutorial,avigad/tutorial,avigad/tutorial,avigad/tutorial