Deny rustdoc warnings in pre-push script, and fix a doc comment

Author: arnaudgolfouse

.githooks/pre-push

@@ -17,4 +17,5 @@ cargo test --no-run
 restore_cargo_lock
 cargo fmt --check
 cargo clippy --tests -- --D warnings
+RUSTDOCFLAGS="-D warnings" cargo doc --document-private-items --no-deps
 cargo test

src/lib.rs

@@ -69,7 +69,7 @@ pub fn initiate_protocol(stream: TokenStream) -> TokenStream {
     ).into()
 }
 
-/// Wrap the function to be used with the [protocol!].
+/// Wrap the function to be used with the [protocol](https://typst.app/docs/reference/foundations/plugin/).
 ///
 /// # Arguments
 ///