rustdoc: change resize cursor on sidebar

This is based on a report that col-resize isn't working,
but e-resize was. That's not an accurate description of
how it resizes, so let's try this?

Author: notriddle

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

@@ -512,7 +512,7 @@ img {
 .sidebar-resizer {
 	touch-action: none;
 	width: 9px;
-	cursor: col-resize;
+	cursor: ew-resize;
 	z-index: calc(var(--desktop-sidebar-z-index) + 1);
 	position: fixed;
 	height: 100%;