fix: migrate onBrokenMarkdownLinks to markdown.hooks

The top-level onBrokenMarkdownLinks config option is deprecated
in favor of markdown.hooks.onBrokenMarkdownLinks and will be
removed in Docusaurus v4.

Signed-off-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>

web/docusaurus.config.ts

@@ -21,7 +21,12 @@ const config: Config = {
   deploymentBranch: 'gh-pages',
 
   onBrokenLinks: 'throw',
-  onBrokenMarkdownLinks: 'throw',
+
+  markdown: {
+    hooks: {
+      onBrokenMarkdownLinks: 'throw',
+    },
+  },
 
   // Even if you don't use internationalization, you can use this field to set
   // useful metadata like html lang. For example, if your site is Chinese, you