doc(GroupTheory): fix file refs (leanprover-community#33305)

Fix some stale documentation file refs.

Author: harahu

Mathlib/GroupTheory/Abelianization/Defs.lean

@@ -12,7 +12,7 @@ public import Mathlib.GroupTheory.Commutator.Basic
 
 This file defines the commutator and the abelianization of a group. It furthermore prepares for the
 result that the abelianization is left adjoint to the forgetful functor from abelian groups to
-groups, which can be found in `Mathlib/Algebra/Category/GrpCat/Adjunctions.lean`.
+groups, which can be found in `Mathlib/Algebra/Category/Grp/Adjunctions.lean`.
 
 ## Main definitions
 

Mathlib/GroupTheory/FreeAbelianGroup.lean

@@ -22,7 +22,7 @@ under pointwise addition. In this file, it is defined as the abelianisation
 of the free group on `α`. All the constructions and theorems required to show
 the adjointness of the construction and the forgetful functor are proved in this
 file, but the category-theoretic adjunction statement is in
-`Mathlib/Algebra/Category/GrpCat/Adjunctions.lean`.
+`Mathlib/Algebra/Category/Grp/Adjunctions.lean`.
 
 ## Main definitions
 

Mathlib/GroupTheory/FreeGroup/Basic.lean

@@ -16,7 +16,7 @@ public import Mathlib.Algebra.BigOperators.Group.List.Basic
 
 This file defines free groups over a type. Furthermore, it is shown that the free group construction
 is an instance of a monad. For the result that `FreeGroup` is the left adjoint to the forgetful
-functor from groups to types, see `Mathlib/Algebra/Category/GrpCat/Adjunctions.lean`.
+functor from groups to types, see `Mathlib/Algebra/Category/Grp/Adjunctions.lean`.
 
 ## Main definitions
 

Mathlib/GroupTheory/GroupAction/DomAct/ActionHom.lean

@@ -16,7 +16,7 @@ into a separate file, not with the definition of `DomMulAct`.
 
 ## TODO
 
-Add left actions of, e.g., `M` on `α →[N] β` to `Mathlib/Algebra/Hom/GroupAction.lean` and
+Add left actions of, e.g., `M` on `α →[N] β` to `Mathlib/Algebra/Group/Action/Hom.lean` and
 `SMulCommClass` instances saying that left and right actions commute.
 -/
 

Mathlib/GroupTheory/GroupExtension/Defs.lean

@@ -46,7 +46,8 @@ If `N` is abelian,
 
 - there is a bijection between `N`-conjugacy classes of
   `(SemidirectProduct.toGroupExtension φ).Splitting` and `groupCohomology.H1`
-  (which will be available in `GroupTheory/GroupExtension/Abelian.lean` to be added in a later PR).
+  (which will be available in the planned file `Mathlib/GroupTheory/GroupExtension/Abelian.lean` to
+  be added in a later PR).
 - there is a bijection between equivalence classes of group extensions and `groupCohomology.H2`
   (which is also stated as a TODO in `Mathlib/RepresentationTheory/GroupCohomology/LowDegree.lean`).
 -/

Mathlib/GroupTheory/Perm/Sign.lean

@@ -25,7 +25,7 @@ public import Mathlib.Data.Finset.Sigma
 The main definition of this file is `Equiv.Perm.sign`,
 associating a `ℤˣ` sign with a permutation.
 
-Other lemmas have been moved to `Mathlib/GroupTheory/Perm/Fintype.lean`
+Other lemmas have been moved to `Mathlib/GroupTheory/Perm/Finite.lean`
 
 -/
 

Mathlib/GroupTheory/Submonoid/Inverses.lean

@@ -20,8 +20,8 @@ For the pointwise inverse of submonoids of groups, please refer to the file
 `Mathlib/Algebra/Group/Submonoid/Pointwise.lean`.
 
 `N.leftInv` is distinct from `N.units`, which is the subgroup of `Mˣ` containing all units that are
-in `N`. See the implementation notes of `Mathlib/GroupTheory/Submonoid/Units.lean` for more details
-on related constructions.
+in `N`. See the implementation notes of `Mathlib/Algebra/Group/Submonoid/Units.lean` for more
+details on related constructions.
 
 ## TODO