Add weta guide on IBL (#66)

* Add weta guide on IBL

* Update index.html

Author: ShadowMitia

resources/index.html

@@ -76,6 +76,9 @@
 		* [Filmic Worlds Blog](http://filmicworlds.com/blog/)
 		* [High Dynamic Range Imaging Book](https://www.cl.cam.ac.uk/~rkm38/pdfs/mantiuk15hdri.pdf)
 		* [Tone Mapping (slides)](https://www.cl.cam.ac.uk/~rkm38/pdfs/tone_mapping.pdf)
+		
+		## Image-Based Lighting
+		* [The Definitive Weta Digital Guide to IBL](https://www.fxguide.com/fxfeatured/the-definitive-weta-digital-guide-to-ibl/)
 
 		# Various Related Resources
 		* [Fix Your Timestep](https://gafferongames.com/post/fix_your_timestep/)