Small fix to DevTools release notes generator (#9544)

Author: elliette

tool/lib/commands/release_notes_helper.dart

@@ -144,9 +144,9 @@ class ReleaseNotesCommand extends Command {
 
     final metadataHeader = '''---
 title: DevTools $releaseNotesVersion release notes
-short-title: $releaseNotesVersion release notes
+shortTitle: $releaseNotesVersion release notes
 breadcrumb: $releaseNotesVersion
-toc: false
+showToc: false
 ---
 
 ''';