Update filesize.nu

Simplified command, improved performance by using ls native directory size flag instead of running du in a loop

cool_oneliners/filesize.nu

@@ -1,2 +1,2 @@
 ## show directory sizes in current directory starting from the largest
-ls|where type == Dir|each {du $it.name}|sort-by apparent|reverse|format filesize apparent GB
+ls -d|where type == Dir|sort-by size|reverse|format filesize apparent GB