Update README.md

Geekhyt · web-flow · commit 7c842c633b96 · 2021-02-02T00:50:30.000+08:00
diff --git a/README.md b/README.md
@@ -24,3 +24,4 @@
 
 - [94. 二叉树的中序遍历](https://github.com/Geekhyt/javascript-leetcode/issues/13)
 - [144. 二叉树的前序遍历](https://github.com/Geekhyt/javascript-leetcode/issues/14)
+- [145. 二叉树的后序遍历](https://github.com/Geekhyt/javascript-leetcode/issues/15)

Original file line number	Diff line number	Diff line change
`@@ -24,3 +24,4 @@`
`24`	`24`
`25`	`25`	`- [94. 二叉树的中序遍历](https://github.com/Geekhyt/javascript-leetcode/issues/13)`
`26`	`26`	`- [144. 二叉树的前序遍历](https://github.com/Geekhyt/javascript-leetcode/issues/14)`
	`27`	`+- [145. 二叉树的后序遍历](https://github.com/Geekhyt/javascript-leetcode/issues/15)`