Update docs/source/contributing/style-guide.md

Co-authored-by: Steve Piercy <[email protected]>

docs/source/contributing/style-guide.md

@@ -36,7 +36,7 @@ Look at the current components [Storybook build](https://6.docs.plone.org/storyb
 
 Recently, Albert updated Pastanaga UI to align with current trends and feedback, creating Quanta — a version 2.0 of Pastanaga UI.
 This reflects ongoing refinement and enhancement of the design system.
-Check out Quanta's appearance in this PDF: {download}`Quanta Spring 2021 <Quanta.pdf>`
+Check out Quanta's appearance in this PDF: {download}`Quanta Spring 2021 <Quanta.pdf>`.
 
 Its implementation has been challenging due to the community's emphasis on stability and the lack of demand from projects.
 While Quanta offers significant improvements, updating JavaScript and CSS poses a barrier for many.