Fix code highlight: remove 'markdown' from automatic language detection. (#8882)

Author: isoos

third_party/highlight/init.js

@@ -1 +1,24 @@
+hljs.configure({
+  // The list of languages that may be used in the auto-detection.
+  // NOTE: always derive this list from the `readme.md`.
+  languages: [
+    'bash',
+    'c',
+    'css',
+    'dart',
+    'diff',
+    'java',
+    'javascript',
+    'json',
+    'kotlin',
+    // removal reason: https://github.com/highlightjs/highlight.js/issues/4279#issuecomment-3126165923
+    // 'markdown',
+    'objectivec',
+    'plaintext',
+    'shell',
+    'swift',
+    'xml',
+    'yaml',
+  ]
+});
 hljs.highlightAll();

third_party/highlight/readme.md

@@ -10,6 +10,8 @@
 4. Verify that the listed language are selected.
 5. Download and extract assets.
 
+**NOTE:** when updating this list, also update the `init.js`.
+
 ```javascript
 var selected = [
   'bash',