mathlib

8b33d740 - chore(group_theory/specific_groups/*): new folder specific_groups (#7018)

chore(group_theory/specific_groups/*): new folder specific_groups (#7018) This creates a new folder `specific_groups` analogous to `analysis.special_functions`. So far, I have put `cyclic` (split from `order_of_element`), `dihedral`, and `quaternion` there. Related Zulip discussion: https://leanprover.zulipchat.com/#narrow/stream/113488-general/topic/group_theory.2Especific_groups