feat(category_theory): images (#2100)
* feat(category_theory): images
* oops, forgot to add file
* Update src/category_theory/category/default.lean
Co-Authored-By: Johan Commelin <johan@commelin.net>
* some improvements
* linting
* oops
* Update src/category_theory/limits/shapes/images.lean
Co-authored-by: Johan Commelin <johan@commelin.net>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
