Update README.md

Geekhyt · web-flow · commit b58d88a42cf4 · 2021-02-05T00:14:49.000+08:00
diff --git a/README.md b/README.md
@@ -35,3 +35,4 @@
 
 - [20. 有效的括号](https://github.com/Geekhyt/javascript-leetcode/issues/21)
 - [84. 柱状图中最大的矩形](https://github.com/Geekhyt/javascript-leetcode/issues/22)
+- [155. 最小栈](https://github.com/Geekhyt/javascript-leetcode/issues/23)

Original file line number	Diff line number	Diff line change
`@@ -35,3 +35,4 @@`
`35`	`35`
`36`	`36`	`- [20. 有效的括号](https://github.com/Geekhyt/javascript-leetcode/issues/21)`
`37`	`37`	`- [84. 柱状图中最大的矩形](https://github.com/Geekhyt/javascript-leetcode/issues/22)`
	`38`	`+- [155. 最小栈](https://github.com/Geekhyt/javascript-leetcode/issues/23)`