Fix typo in style guide

docs/dev/style.md

@@ -294,8 +294,9 @@ Prefer `Default` even it has to be implemented manually.
 
 **Rationale:** less typing in the common case, uniformity.
 
-Use `Vec::new` rather than `vec![]`. **Rationale:** uniformity, strength
-reduction.
+Use `Vec::new` rather than `vec![]`.
+
+**Rationale:** uniformity, strength reduction.
 
 ## Functions Over Objects
 
@@ -479,7 +480,7 @@ pub fn reachable_nodes(node: Node) -> FxHashSet<Node> {
 }
 ```
 
-**Rational:** re-use allocations, accumulator style is more concise for complex cases.
+**Rationale:** re-use allocations, accumulator style is more concise for complex cases.
 
 # Style