mathlib3

708faa9f - feat(geometry/manifold/manifold): define manifolds (#1422)

feat(geometry/manifold/manifold): define manifolds (#1422) * feat(geometry/manifold/manifold): define manifolds * Update src/geometry/manifold/manifold.lean Typo Co-Authored-By: Johan Commelin <johan@commelin.net> * reviewer comments * notations, comments * Update src/geometry/manifold/manifold.lean Co-Authored-By: Scott Morrison <scott@tqft.net> * Update src/geometry/manifold/manifold.lean Co-Authored-By: Scott Morrison <scott@tqft.net> * manifolds: reviewers comments * comment on notation for composition * add documentation on atlases and structomorphisms