Fix broken link to hljs.ts in documentation

Co-authored-by: reakaleek <[email protected]>

Author: Copilot

docs/syntax/code.md

@@ -404,5 +404,5 @@ This `code` is inline.
 
 ## Supported Languages
 
-Please refer to [hljs.ts](https://github.com/elastic/docs-builder/blob/main/src/Elastic.Markdown/Assets/hljs.ts)
+Please refer to [hljs.ts](https://github.com/elastic/docs-builder/blob/main/src/Elastic.Documentation.Site/Assets/hljs.ts)
 for a complete list of supported languages.