fix: 0->ø (trekhleb#486)

Author: ly15927086342

src/data-structures/linked-list/README.zh-CN.md

@@ -101,7 +101,7 @@ Traverse(head)
   Pre: head is the head node in the list
   Post: the items in the list have been traversed
   n ← head
-  while n != 0
+  while n != ø
     yield n.value
     n ← n.next
   end while