update link

internals/parser.rst

@@ -804,10 +804,10 @@ Generating AST objects
 The output of the C parser used by CPython that is generated by the
 :cpy-file:`Grammar/python.gram` grammar file is a Python AST object (using C
 structures). This means that the actions in the grammar file generate AST objects
-when they succeed. Constructing these objects can be quite cumbersome (see
-the :ref:`AST compiler section <compiler-ast-trees>` for more information
-on how these objects are constructed and how they are used by the compiler) so
-special helper functions are used. These functions are declared in the
+when they succeed. Constructing these objects can be quite cumbersome (see the
+`AST compiler section <https://github.com/python/cpython/blob/main/InternalDocs/compiler.md#abstract-syntax-trees-ast>`_
+for more information on how these objects are constructed and how they are used
+by the compiler) so special helper functions are used. These functions are declared in the
 :cpy-file:`Parser/pegen.h` header file and defined in the :cpy-file:`Parser/action_helpers.c`
 file. These functions allow you to join AST sequences, get specific elements
 from them or to do extra processing on the generated tree.