[MLIR][Docs] Fix broken link to tuple type rationale

mlir/include/mlir/IR/BuiltinTypes.td

let description = [{
     tuple-type ::= `tuple` `<` (type ( `,` type)*)? `>`
     ```
 
     The value of `tuple` type represents a fixed-size collection of elements,
     where each element may be of a different type.
 
     **Rationale:** Though this type is first class in the type system, MLIR
     provides no standard operations for operating on `tuple` types
-    ([rationale](Rationale/Rationale.md/#tuple-types)).
+    ([rationale](Rationale/Rationale/#tuple-types)).
 
     Examples:
 
     ```mlir
     // Empty tuple.
     tuple<>
 
     // Single element