Fixed broken links.

src/docs/asciidoc/sdk/terrain_editor.adoc

@@ -106,7 +106,7 @@ Essentially if your scale in normal texture coordinates is 16, then for tri-plan
 
 Tri-planar texture mapping is recommended if you have lots of near-vertical terrain. With normal texture mapping the textures can look stretched because it is rendered on the one plane: X-Z. Tri-planar mapping renders the textures on three planes: X-Z, X-Y, Z-Y; and blends them together based on what plane the normal of the triangle is facing most on.
 This makes the terrain look much better, but it does have a performance hit!
-Here is an article on tri-planar mapping: link:http://http.developer.nvidia.com/GPUGems3/gpugems3_ch01.html[http://http.developer.nvidia.com/GPUGems3/gpugems3_ch01.html]
+Here is an article on tri-planar mapping: link:https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_ch01.html[https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_ch01.html]
 
 
 === Total texture count