Fix more broken links.

engine/guidelines/cpp_usage_guidelines.rst

@@ -52,15 +52,11 @@ Standard Template Library
 
 We don't allow using the `STL <https://en.wikipedia.org/wiki/Standard_Template_Library>`__
 as Godot provides its own data types (among other things).
-See :ref:`doc_faq_why_not_stl` for more information.
+See `Why does Godot not use STL? <https://docs.godotengine.org/en/stable/about/faq.html#why-does-godot-not-use-stl-standard-template-library>`__ for more information.
 
 This means that pull requests should **not** use ``std::string``,
 ``std::vector`` and the like. Instead, use Godot's datatypes as described in
-the :ref:`doc_core_types` documentation.
-
-A 📜 icon denotes the type is part of :ref:`Variant <doc_variant_class>`. This
-means it can be used as a parameter or return value of a method exposed to the
-scripting API.
+the `Core types <https://docs.godotengine.org/en/latest/engine_details/architecture/core_types>`__ documentation.
 
 ``auto`` keyword
 ~~~~~~~~~~~~~~~~
@@ -121,7 +117,7 @@ guards are now actively discouraged.
 C++ style exception handling using ``try`` and ``catch`` blocks is forbidden.
 This restriction is in place for several reasons, including performance, binary
 size and code complexity.
-Use :ref:`doc_common_engine_methods_and_macros_error_macros` instead.
+Use `Common engine methods and macros <https://docs.godotengine.org/en/latest/engine_details/architecture/common_engine_methods_and_macros.html>`__ instead.
 
 
 .. seealso::

engine/guidelines/editor_style_guide.rst

@@ -54,7 +54,7 @@ contain few items make it difficult to navigate the inspector, while missing the
 benefits of using sections such as folding.
 
 There are some valid exceptions for this, such as material features in
-:ref:`class_StandardMaterial3D`.
+`StandardMaterial3D <https://docs.godotengine.org/en/stable/classes/class_standardmaterial3d.html>`__.
 
 This advice also applies to the Project Settings and Editor Settings.
 

engine/introduction.rst

@@ -1,3 +1,5 @@
+.. _doc_intro_to_engine_contributions:
+
 Introduction to engine contributions
 ====================================