Add SDF Viewer to the README.md

I made a real-time, cross-platform, language-agnostic SDF Viewer application, and integrated it with your SDF library among others. It works similarly to `sdf3ui` but has some extra features (AFAIK):

- Different rendering algorithm that allows observing the model preview while it is being loaded.
- Support for customizing parameters in real-time from the UI without modifying the code (it also listens for code changes and refreshes the view)
- Support for textures and material properties (and even exporting them).
- You can publish your SDF by uploading a file to a server and sharing the renderer link (renders the SDF in the browser without a backend).
- More meshing algorithms (although speed is not a concern).

Check out https://github.com/Yeicor/sdf-viewer and https://github.com/Yeicor/sdf-viewer-go for much more information.

README.md

@@ -9,7 +9,7 @@
 A rewrite of the original CAD package [`sdfx`](https://github.com/deadsy/sdfx) for generating 2D and 3D geometry using [Go](https://go.dev/).
 
 ## Highlights
-* GUI with real-time rendering using [sdf3ui](https://github.com/soypat/sdf3ui).
+* GUI with real-time rendering using [sdf3ui](https://github.com/soypat/sdf3ui) (or [SDF Viewer](https://github.com/Yeicor/sdf-viewer-go)).
 * 3d and 2d objects modelled with signed distance functions (SDFs).
 * Minimal and idiomatic API.
 * Render objects as triangles or save to STL, 3MF(experimental) file format.
@@ -130,4 +130,4 @@ None planned.
 ## Logo work
 Gopher rendition by [Juliette Whittingslow](https://www.instagram.com/artewitty/).  
 Gopher design authored by [Renée French](https://www.instagram.com/reneefrench)
-is licensed by the Creative Commons Attribution 3.0 licensed.
+is licensed by the Creative Commons Attribution 3.0 licensed.