Fix link to "Updating LLVM" documentation (#42)
The documentation was moved and is no longer accessible through the old link.
diff --git a/README.md b/README.md
index 53204a6..a9e11bd 100644
--- a/README.md
+++ b/README.md
@@ -11,4 +11,4 @@
To learn more about updating LLVM in the Rust compiler, consult the
[documentation for doing so in
-`rustc-guide`](https://rust-lang.github.io/rustc-guide/codegen/updating-llvm.html)
+`rustc-guide`](https://rustc-dev-guide.rust-lang.org/backend/updating-llvm.html)
