Update Editor icons information to follow changes in the `master` branch

See https://github.com/godotengine/godot/pull/36513.

development/editor/creating_icons.rst

@@ -11,47 +11,33 @@ to improve the user experience.
 Creating icons
 ~~~~~~~~~~~~~~
 
-In order to create new icons, you first need a vector graphics editor installed.
-For instance, you can use the open-source `Inkscape <https://inkscape.org/>`_ editor.
+To create new icons, you first need a vector graphics editor installed.
+For instance, you can use the open source `Inkscape <https://inkscape.org/>`_ editor.
 
-Clone the ``godot-design`` repository containing all the original editor icons:
+Clone the ``godot`` repository containing all the editor icons:
 
    .. code-block:: bash
 
-       git clone https://github.com/godotengine/godot-design
+       git clone https://github.com/godotengine/godot
 
-The icons must be created in a vector graphics editor in ``svg`` format. You
-can use ``engine/icons/inkscape_template.svg`` with default icon properties
-already set up.
+The icons must be created in a vector graphics editor in SVG format. There are
+two main requirements to follow:
 
-Once you're satisfied with the icon's design, save the icon in
-``engine/icons/svg/`` folder. But in order for the engine to automatically
-pick up the icons, each icon's filename:
+- Icons must be 16×16. In Inkscape, you can configure the document size in
+  **File > Document Properties**.
+- Lines should be snapped to pixels whenever possible to remain crisp at lower DPI.
+  You can create a 16×16 grid in Inkscape to make this easier.
 
-1. Must be prefixed with ``icon_``.
-
-2. ``PascalCase`` name should be converted to ``snake_case``, so words
-   are separated by ``_`` whenever case changes, and uppercase acronyms must
-   also have all letters, numbers, and special characters separated as distinct
-   words. Some examples:
-
-   +--------------------+----------------------------------+
-   | Name               | Filename                         |
-   +====================+==================================+
-   | ``Polygon2D``      | ``icon_polygon_2_d.svg``         |
-   +--------------------+----------------------------------+
-   | ``CSGPolygon``     | ``icon_c_s_g_polygon.svg``       |
-   +--------------------+----------------------------------+
-   | ``CPUParticles2D`` | ``icon_c_p_u_particles_2_d.svg`` |
-   +--------------------+----------------------------------+
-   | ``C#``             | ``icon_c_#.svg``                 |
-   +--------------------+----------------------------------+
+Once you're satisfied with the icon's design, save the icon in the cloned
+repository's ``editor/icons`` folder. The icon name should match the intended
+name in a case-sensitive manner. For example, to create an icon for
+CPUParticles2D, name the file ``CPUParticles2D.svg``.
 
 Icon optimization
 ~~~~~~~~~~~~~~~~~
 
-Because the editor renders the ``svg``'s at runtime, they need to be small
-in size, so they can be efficiently parsed. Editor icons must be first
+Because the editor renders SVGs once at load time, they need to be small
+in size so they can be efficiently parsed. Editor icons must be first
 optimized before being added to the engine, to do so:
 
 1. Add them to the ``engine/icons/svg`` folder.
@@ -69,10 +55,8 @@ Integrating and sharing the icons
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 If you're contributing to the engine itself, you should make a pull request to
-add optimized icons to ``godot/editor/icons`` in the main repository. Recompile
-the engine to make sure it does pick up new icons for classes. Once merged,
-don't forget to add the original version of the icons to the ``godot-design``
-repository so that the icon can be improved upon by other contributors.
+add optimized icons to ``editor/icons`` in the main repository. Recompile the
+engine to make it pick up new icons for classes.
 
 It's also possible to create custom icons within a module. If you're creating
 your own module and don't plan to integrate it with Godot, you don't need to
@@ -89,10 +73,10 @@ If icons don't appear in the editor make sure that:
 
 1. Each icon's filename matches the naming requirement as described previously.
 
-2. ``modules/svg`` is enabled (should be enabled by default). Without it, icons
-   won't appear in the editor at all.
+2. ``modules/svg`` is enabled (it should be enabled by default). Without it,
+   icons won't appear in the editor at all.
 
-References:
-~~~~~~~~~~~
+References
+~~~~~~~~~~
 
 -  `editor/icons <https://github.com/godotengine/godot/tree/master/editor/icons>`__