Small fix to DevTools release notes generator  (#9544)

tool/lib/commands/release_notes_helper.dart

diff --git a/tool/lib/commands/release_notes_helper.dart b/tool/lib/commands/release_notes_helper.dart
index 494447e..0f8e471 100644
--- a/tool/lib/commands/release_notes_helper.dart
+++ b/tool/lib/commands/release_notes_helper.dart
@@ -144,9 +144,9 @@
 
     final metadataHeader = '''---
 title: DevTools $releaseNotesVersion release notes
-short-title: $releaseNotesVersion release notes
+shortTitle: $releaseNotesVersion release notes
 breadcrumb: $releaseNotesVersion
-toc: false
+showToc: false
 ---
 
 ''';