Clarify "res" to "resolution"

sphinx/builders/html/__init__.py

@@ -891,7 +891,7 @@ def cleanup(self) -> None:
 
     def post_process_images(self, doctree: Node) -> None:
         """Pick the best candidate for an image and link down-scaled images to
-        their high res version.
+        their high resolution version.
         """
         super().post_process_images(doctree)