Link to ThorVG's SVG support page in Importing images

The page lists which features of the SVG specification are supported.

tutorials/assets_pipeline/importing_images.rst

@@ -24,7 +24,8 @@ Godot can import the following image formats:
 - Truevision Targa (``.tga``)
 - SVG (``.svg``, ``.svgz``)
   - SVGs are rasterized using `ThorVG <https://www.thorvg.org/>`__
-  when importing them. Support is limited; complex vectors may not render correctly.
+  when importing them. `Support is limited <https://www.thorvg.org/about#:~:text=among%20the%20svg%20tiny%20specs%2C%20yet%20unsupported%20features%20in%20the%20thorvg%20are%20the%20following>`__;
+  complex vectors may not render correctly.
   You can check whether ThorVG can render a certain vector correctly using its
   `web-based viewer <https://www.thorvg.org/viewer>`__.
   For complex vectors, rendering them to PNGs using `Inkscape <https://inkscape.org/>`__