feat(A1): add some information to the Quick Reference
feat(A1): add some information to the Quick Reference

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