doc(algebra/group/type_tags): add docs (#2287)
* doc(algebra/group/type_tags): add docs
* Update src/algebra/group/type_tags.lean
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: sgouezel <sebastien.gouezel@univ-rennes1.fr>
