Normalize workspace shadows to 1080 px tall screen, adjust defaults

Workspace gaps are dependent on screen size, so it makes sense to make shadows
depend on the screen size to, to avoid them filling more or less of the gap.

wiki/Configuration:-Miscellaneous.md

@@ -29,9 +29,9 @@ overview {
 
     workspace-shadow {
         // off
-        softness 120
-        spread 20
-        offset x=0 y=20
+        softness 80
+        spread 10
+        offset x=0 y=10
         color "#00000070"
     }
 }
@@ -192,7 +192,7 @@ Control the shadow behind workspaces visible in the overview.
 
 Settings here mirror the normal [`shadow` config in the layout section](./Configuration:-Layout.md#shadow), so check the documentation there.
 
-Keep in mind that workspace shadows are configured for the full-screen workspace size, then zoomed out together with the workspace.
+Workspace shadows are configured for a workspace size normalized to 1080 pixels tall, then zoomed out together with the workspace.
 Practically, this means that you'll want bigger spread, offset, and softness compared to window shadows.
 
 ```kdl