Point standard library links to stable

Author: dtolnay

Cargo.toml

@@ -29,7 +29,12 @@ syn = { version = "2.0.96", default-features = false, features = ["clone-impls",
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
-rustdoc-args = ["--generate-link-to-definition"]
+rustdoc-args = [
+    "--generate-link-to-definition",
+    "--extern-html-root-url=core=https://doc.rust-lang.org",
+    "--extern-html-root-url=alloc=https://doc.rust-lang.org",
+    "--extern-html-root-url=std=https://doc.rust-lang.org",
+]
 
 [package.metadata.playground]
 features = ["verbatim"]