docs(group_theory/semidirect_product): fix typo in module docs (#12083)

src/group_theory/semidirect_product.lean

@@ -12,7 +12,7 @@ import group_theory.subgroup.basic
 
 This file defines semidirect products of groups, and the canonical maps in and out of the
 semidirect product. The semidirect product of `N` and `G` given a hom `φ` from
-`φ` from `G` to the automorphism group of `N` is the product of sets with the group
+`G` to the automorphism group of `N` is the product of sets with the group
 `⟨n₁, g₁⟩ * ⟨n₂, g₂⟩ = ⟨n₁ * φ g₁ n₂, g₁ * g₂⟩`
 
 ## Key definitions