feat(v2): onBrokenMarkdownLinks config (#3658)

* refactor(v2): move `reportMessage` from `core/src/server/utils` to `utils` package

* feat(v2): handle broken markdown links by using onBrokenLinks prop from siteconfig

* feat(v2): add a new site config prop called `onBrokenMarkdownLinks`

works like onBrokenLinks, but only for markdown links

* feat(v2): add `onBrokenMarkdownLinks` to API docs

* some changes regarding test issues after adding `onBrokenMarkdownLink`

* Update website/versioned_docs/version-2.0.0-alpha.66/api/docusaurus.config.js.md

Co-authored-by: Sébastien Lorber <slorber@users.noreply.github.com>

website/docs/api/docusaurus.config.js.md

@@ -108,6 +108,14 @@ The broken links detection is only available for a production build (`docusaurus
 
 :::
 
+### `onBrokenMarkdownLinks`
+
+- Type: `'ignore' | 'log' | 'warn' | 'error' | 'throw'`
+
+The behavior of Docusaurus, when it detects any broken markdown link.
+
+By default, it prints a warning, to let you know about your broken markdown link, but you can change this security if needed.
+
 ### `onDuplicateRoutes`
 
 - Type: `'ignore' | 'log' | 'warn' | 'error' | 'throw'`

website/docusaurus.config-blog-only.js

@@ -13,6 +13,7 @@ module.exports = {
   baseUrl: '/blog-only/',
   url: 'https://v2.docusaurus.io',
   onBrokenLinks: 'throw',
+  onBrokenMarkdownLinks: 'warn',
   favicon: 'img/docusaurus.ico',
   themes: ['@docusaurus/theme-live-codeblock'],
   plugins: [],

website/docusaurus.config.js

@@ -49,6 +49,7 @@ module.exports = {
   baseUrl,
   url: 'https://v2.docusaurus.io',
   onBrokenLinks: isVersioningDisabled ? 'warn' : 'throw',
+  onBrokenMarkdownLinks: 'warn',
   favicon: 'img/docusaurus.ico',
   customFields: {
     description: