diff --git a/docs/usage.md b/docs/usage.md
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -8,2 +8,3 @@ Run the command from the repository root.
-Use the old flag.
+Use the new flag.
+The old flag still works for one release.
diff --git a/src/summary.js b/src/summary.js
--- a/src/summary.js
+++ b/src/summary.js
@@ -1,3 +1,4 @@
 export function summarize(lines) {
-  return lines.join("\n");
+  return lines.join("\n").trim();
 }
+// Keep the trailing newline out of release notes.
diff --git a/tests/summary.test.js b/tests/summary.test.js
--- a/tests/summary.test.js
+++ b/tests/summary.test.js
@@ -1,2 +1,3 @@
 test("joins lines", () => {
   assert.equal(summarize(["a", "b"]), "a\nb");
 });
+test("trims outer whitespace", () => assert.equal(summarize([" a "]), "a"));