Delete more LLM-generated comments from the migration

lean/Spa/Showable.lean

@@ -1,16 +1,8 @@
-/-
-Port of `Showable.agda` (plus the `Showable` instances that lived on
-`Lattice/Map.agda` and `Lattice/AboveBelow.agda`).
-
-Lean has `ToString`, but its `String` instance does not quote (the Agda one
-does), so to reproduce the Agda output exactly we port the class as-is.
--/
 import Spa.Lattice.FiniteMap
 import Spa.Lattice.AboveBelow
 
 namespace Spa
 
-/-- Agda: `Showable` (`show` is a Lean keyword, hence `show'`). -/
 class Showable (α : Type*) where
   show' : α → String
 
@@ -29,15 +21,12 @@ instance {α β : Type*} [Showable α] [Showable β] : Showable (α × β) :=
 
 instance : Showable PUnit := ⟨fun _ => "()"⟩
 
-/-- Agda: the `Showable` instance of `Lattice/AboveBelow.agda`. -/
 instance {α : Type*} [Showable α] : Showable (AboveBelow α) :=
   ⟨fun
     | .bot => "⊥"
     | .top => "⊤"
     | .mk x => show' x⟩
 
-/-- Agda: the `Showable` instance of `Lattice/Map.agda` (inherited by
-`FiniteMap`). -/
 instance {α β : Type*} {ks : List α} [Showable α] [Showable β] :
     Showable (FiniteMap α β ks) :=
   ⟨fun fm =>