doc(Combinatorics): fix file refs (leanprover-community#33272)

Fix some stale documentation file refs.

Author: harahu

Mathlib/Combinatorics/Enumerative/DyckWord.lean

@@ -486,8 +486,8 @@ set_option backward.privateInPublic true in
 `f(0) = nil`. For a nonzero word find the `D` that matches the initial `U`,
 which has index `p.firstReturn`, then let `x` be everything strictly between said `U` and `D`,
 and `y` be everything strictly after said `D`. `p = x.nest + y` with `x, y` (possibly empty)
-Dyck words. `f(p) = f(x) △ f(y)`, where △ (defined in `Mathlib/Data/Tree.lean`) joins two subtrees
-to a new root node. -/
+Dyck words. `f(p) = f(x) △ f(y)`, where △ (defined in `Mathlib/Data/Tree/Basic.lean`) joins two
+subtrees to a new root node. -/
 private def equivTreeToFun (p : DyckWord) : Tree Unit :=
   if h : p = 0 then nil else
     have := semilength_insidePart_lt h

Mathlib/Combinatorics/Matroid/Rank/Cardinal.lean

@@ -36,12 +36,12 @@ both for itself and all its minors.
 
 It is not (provably) the case that all matroids are `InvariantCardinalRank`,
 since the equicardinality of bases in general matroids is independent of ZFC
-(see the module docstring of `Mathlib/Data/Matroid/Basic.lean`).
+(see the module docstring of `Mathlib/Combinatorics/Matroid/Basic.lean`).
 Lemmas like `Matroid.Base.cardinalMk_diff_comm` become true for all matroids
 only if they are weakened by replacing `Cardinal.mk` with the cruder `ℕ∞`-valued `Set.encard`.
 The `ℕ∞`-valued rank and rank functions `Matroid.eRank` and `Matroid.eRk`,
 which have a more unconditionally strong API,
-are developed in `Mathlib/Data/Matroid/Rank/ENat.lean`.
+are developed in `Mathlib/Combinatorics/Matroid/Rank/ENat.lean`.
 
 ## Implementation Details
 

Mathlib/Combinatorics/Matroid/Rank/ENat.lean

@@ -46,7 +46,7 @@ which is why mathlib defines matroids using bases/independence. )
 It is natural to ask if equicardinality of bases holds if 'cardinality' refers to
 a term in `Cardinal` instead of `ℕ∞`, but the answer is that it doesn't.
 The cardinal-valued rank functions `Matroid.cRank` and `Matroid.cRk` are defined in
-`Mathlib/Data/Matroid/Rank/Cardinal.lean`, but have less desirable properties in general.
+`Mathlib/Combinatorics/Matroid/Rank/Cardinal.lean`, but have less desirable properties in general.
 See the module docstring of that file for a discussion.
 
 ## Implementation Details