Update modules/os2forms_digital_post/README.md

Co-authored-by: Mikkel Ricky <rimi@aarhus.dk>

Author: jekuaitk

modules/os2forms_digital_post/README.md

@@ -158,7 +158,7 @@ With extended address information and c/o:
 
 ### Styling of the HTML
 
-The following SCSS can be used to style the injected HTML accordingly:
+The following [SCSS](https://sass-lang.com/) can be used to style the injected HTML accordingly:
 
 ```scss
 $margin-top: 25mm;