Update article.md

Author: jeremiahschung

_style_guide/article.md

@@ -55,7 +55,7 @@ This is body copy after an ordered list. Lorem ipsum dolor sit amet, consectetur
 
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-![Here's an image](http://via.placeholder.com/1000x200/e44c2c/ffffff "Sample image")
+![Here's an image](https://via.placeholder.com/1000x200/e44c2c/ffffff "Sample image")
 
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