mathlib

64d953a1 - refactor(set_theory/ordinal): `enum_lt` → `enum_lt_enum` (#12469)

refactor(set_theory/ordinal): `enum_lt` → `enum_lt_enum` (#12469) That way, the theorem name matches that of `enum_le_enum`, `typein_lt_typein`, and `typein_le_typein`.