Add localized class reference as pre-generated RST files

Currently including `zh_CN` and `es` which both have very high completion
ratios. Others will be added once they reach a significant percentage too.

These RST files will be used by godot-docs in place of its `classes` folder
after we sync with https://github.com/godotengine/godot-docs/pull/5458.

The update workflow is manual for now (example for `zh_CN`):

- Build `godotengine/godot` in the branch we currently track (now `3.x`)
- Run `godot --doctool -l zh_CN`
- Run `cd doc && make rst LANGARG=zh_CN`
- Copy `doc/_build/rst/*` to `classes/zh_CN/` here
- Make sure to have `classes/zh_CN/index.rst` copied from `docs/classes`

classes/es/class_texture3d.rst

@@ -0,0 +1,50 @@
+:github_url: hide
+
+.. Generated automatically by doc/tools/make_rst.py in Godot's source tree.
+.. DO NOT EDIT THIS FILE, but the Texture3D.xml source instead.
+.. The source is found in doc/classes or modules/<name>/doc_classes.
+
+.. _class_Texture3D:
+
+Texture3D
+=========
+
+**Inherits:** :ref:`TextureLayered<class_TextureLayered>` **<** :ref:`Resource<class_Resource>` **<** :ref:`Reference<class_Reference>` **<** :ref:`Object<class_Object>`
+
+Texture with 3 dimensions.
+
+Descripción
+----------------------
+
+Texture3D is a 3-dimensional :ref:`Texture<class_Texture>` that has a width, height, and depth. See also :ref:`TextureArray<class_TextureArray>`.
+
+\ **Note:** ``Texture3D``\ s can only be sampled in shaders in the GLES3 backend. In GLES2, their data can be accessed via scripting, but there is no way to render them in a hardware-accelerated manner.
+
+Propiedades
+----------------------
+
++-------------------------------------+-------+------------------------------------------------------------------------------------------------------------------------------------------------------+
+| :ref:`Dictionary<class_Dictionary>` | data  | ``{"depth": 0,"flags": 4,"format": 37,"height": 0,"layers": [  ],"width": 0}`` (overrides :ref:`TextureLayered<class_TextureLayered_property_data>`) |
++-------------------------------------+-------+------------------------------------------------------------------------------------------------------------------------------------------------------+
+| :ref:`int<class_int>`               | flags | ``4`` (overrides :ref:`TextureLayered<class_TextureLayered_property_flags>`)                                                                         |
++-------------------------------------+-------+------------------------------------------------------------------------------------------------------------------------------------------------------+
+
+Métodos
+--------------
+
++------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+| void | :ref:`create<class_Texture3D_method_create>` **(** :ref:`int<class_int>` width, :ref:`int<class_int>` height, :ref:`int<class_int>` depth, :ref:`Format<enum_Image_Format>` format, :ref:`int<class_int>` flags=4 **)** |
++------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+
+Descripciones de Métodos
+------------------------------------------------
+
+.. _class_Texture3D_method_create:
+
+- void **create** **(** :ref:`int<class_int>` width, :ref:`int<class_int>` height, :ref:`int<class_int>` depth, :ref:`Format<enum_Image_Format>` format, :ref:`int<class_int>` flags=4 **)**
+
+Creates the Texture3D with specified ``width``, ``height``, and ``depth``. See :ref:`Format<enum_Image_Format>` for ``format`` options. See :ref:`Flags<enum_TextureLayered_Flags>` enumerator for ``flags`` options.
+
+.. |virtual| replace:: :abbr:`virtual (This method should typically be overridden by the user to have any effect.)`
+.. |const| replace:: :abbr:`const (This method has no side effects. It doesn't modify any of the instance's member variables.)`
+.. |vararg| replace:: :abbr:`vararg (This method accepts any number of arguments after the ones described here.)`