docs: add 'Importing Textures'

docs/importing_resources/importing_textures.rst

@@ -1,2 +1,16 @@
+==================
 Importing Textures
 ==================
+
+Textures are usually added to the project indirectly by higher-level
+importers (for example when :ref:`Importing Scenes` or :ref:`Importing
+Sprites`). You can also import images as standalone textures when you need it
+for UI, materials, or other specialized uses.
+
+When you import a texture, Crown copies the source image into
+the :ref:`project <project>` and creates a ``.texture`` resource file with
+the same name. The ``.texture`` resource stores processing settings for each
+target platform (compression, mipmaps etc.). Crown uses the ``.texture`` file
+at compile time to produce optimized GPU-ready assets.
+
+Open the :ref:`Texture Settings` tool to review or modify processing options.