Update book link from Embark to rust-gpu github org.

Author: LegNeato

config.toml

@@ -23,7 +23,7 @@ website_github_repo = "Rust-GPU/rust-gpu.github.io"
 site_description = "Rust on GPUs."
 juice_exclude_menu = ["Ecosystem", "Changelog", "Blog"]
 juice_extra_menu = [
-    { title = "Docs", link = "https://embarkstudios.github.io/rust-gpu/book/" },
+    { title = "Docs", link = "https://rust-gpu.github.io/rust-gpu/book/" },
     { title = "Blog", link = "/blog/" },
     { title = "Ecosystem", link = "/ecosystem/" },
     { title = "Changelog", link = "/changelog/" },