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