Disambiguate the write link in the revision-writing helper's doc

rustdoc reads the bare name as both the function and the std macro, which
the workspace doc check refuses.

swarm-controller/src/schedules.rs

@@ -542,7 +542,7 @@ pub(crate) async fn write<T: Serialize>(
     Ok(write_revision(store, key, value, revision).await?.is_some())
 }
 
-/// As [`write`], answering the revision written, or `None` when another write
+/// As [`write()`], answering the revision written, or `None` when another write
 /// landed first.
 pub(crate) async fn write_revision<T: Serialize>(
     store: &Store,