fix(config): migrate onBrokenMarkdownLinks to markdown.hooks (#36)

This PR migrates the onBrokenMarkdownLinks configuration from the
top-level config to markdown.hooks.onBrokenMarkdownLinks to fix the
deprecation warning and ensure compatibility with Docusaurus v4.

The deprecated top-level configuration was causing the following warning
during the build process:

```
[WARNING] The `siteConfig.onBrokenMarkdownLinks` config option is deprecated and will be removed in Docusaurus v4.
Please migrate and move this option to `siteConfig.markdown.hooks.onBrokenMarkdownLinks` instead.
```

This change follows the recommended migration path by moving the setting
to the new location under markdown.hooks while maintaining the same
behavior (throwing on broken markdown links).

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

Author: mnencia

website/docusaurus.config.ts

@@ -30,7 +30,6 @@ const config: Config = {
   deploymentBranch: 'gh-pages',
 
   onBrokenLinks: 'throw',
-  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
@@ -179,6 +178,9 @@ const config: Config = {
             allowComments: true,
             allowHtml: true,
       },
+      hooks: {
+        onBrokenMarkdownLinks: 'throw',
+      },
     },
     prism: {
       theme: prismThemes.github,