Clean up "Eta reduction for data families" Notes

Before, there were two distinct Notes named
"Eta reduction for data families". This renames one of them to
"Implementing eta reduction for data families" to disambiguate the
two and fixes references in other parts of the codebase to ensure
that they are pointing to the right place.

Fixes #17313.

[ci skip]

1 files changed, 8 insertions, 4 deletions

diff --git a/compiler/GHC/Core/Coercion/Axiom.hs b/compiler/GHC/Core/Coercion/Axiom.hs
index 9b8fb6e067..5dd99a4ac1 100644
--- a/compiler/GHC/Core/Coercion/Axiom.hs
+++ b/compiler/GHC/Core/Coercion/Axiom.hs
@@ -235,7 +235,7 @@ data CoAxBranch
     , cab_tvs      :: [TyVar]       -- Bound type variables; not necessarily fresh
     , cab_eta_tvs  :: [TyVar]       -- Eta-reduced tyvars
                                     -- See Note [CoAxBranch type variables]
-                                    -- cab_tvs and cab_lhs may be eta-reduded; see
+                                    -- cab_tvs and cab_lhs may be eta-reduced; see
                                     -- Note [Eta reduction for data families]
     , cab_cvs      :: [CoVar]       -- Bound coercion variables
                                     -- Always empty, for now.
@@ -443,9 +443,13 @@ looked like
 (See #9692, #14179, and #15845 for examples of what can go wrong if
 we don't eta-expand when showing things to the user.)
 
-(See also Note [Newtype eta] in GHC.Core.TyCon.  This is notionally separate
-and deals with the axiom connecting a newtype with its representation
-type; but it too is eta-reduced.)
+See also:
+
+* Note [Newtype eta] in GHC.Core.TyCon.  This is notionally separate
+  and deals with the axiom connecting a newtype with its representation
+  type; but it too is eta-reduced.
+* Note [Implementing eta reduction for data families] in TcInstDcls. This
+  describes the implementation details of this eta reduction happen.
 -}
 
 instance Eq (CoAxiom br) where