mathlib

084b7e7d - chore(algebra/order,data/set/intervals): a few more trivial lemmas (#4611)

chore(algebra/order,data/set/intervals): a few more trivial lemmas (#4611) * a few more lemmas for `has_le.le` and `has_lt.lt` namespaces; * a few lemmas about intersections of intervals; * fix section header in `topology/algebra/module`.