docs: remove fourth permutation of the visit API (#4473)

The fourth permutation was removed in
#2957

See #4466

---------

Co-authored-by: Yaacov Rydzinski <yaacovCR@gmail.com>

Author: janmeier

website/pages/api-v16/language.mdx

@@ -219,7 +219,7 @@ const editedAST = visit(ast, {
 
 Alternatively to providing enter() and leave() functions, a visitor can
 instead provide functions named the same as the kinds of AST nodes, or
-enter/leave visitors at a named key, leading to four permutations of
+enter/leave visitors at a named key, leading to three permutations of
 visitor API:
 
 1. Named visitors triggered when entering a node a specific kind.
@@ -261,23 +261,6 @@ visit(ast, {
 });
 ```
 
-4. Parallel visitors for entering and leaving nodes of a specific kind.
-
-```js
-visit(ast, {
-  enter: {
-    Kind(node) {
-      // enter the "Kind" node
-    },
-  },
-  leave: {
-    Kind(node) {
-      // leave the "Kind" node
-    },
-  },
-});
-```
-
 ### `BREAK`
 
 The sentinel `BREAK` value described in the documentation of `visitor`.