rustdoc: remove no-op CSS .block { padding: 0 }

This rule was changed in 8fb1250 from the
original version that had a non-zero padding. It's not needed, because
it's not overriding anything that would've given `.block` a padding.

Author: notriddle

src/librustdoc/html/static/css/rustdoc.css

@@ -498,9 +498,6 @@ img {
 	font-weight: 500;
 }
 
-.block {
-	padding: 0;
-}
 .block ul, .block li {
 	padding: 0;
 	margin: 0;