Apply suggestions from code review

Co-authored-by: Lee Calcote <leecalcote@gmail.com>
Signed-off-by: Rishi Raj <rishiraj438gt@gmail.com>

Author: rishiraj38

src/collections/news/news-template/0000-00-00-news-title/index.mdx

@@ -6,7 +6,7 @@ author: The Newsroom
 thumbnail_svg: ./sample.svg
 darkthumbnail_svg: ./sample.svg
 eurl: https://www.example.com/some/other/site
-source_url: https://original-source.com/article
+source_url: https://original-source.com/article (Optional)
 published: false
 ---