Update README.md

Geekhyt · web-flow · commit 9486d3f3930a · 2021-02-04T18:38:42.000+08:00
diff --git a/README.md b/README.md
@@ -34,3 +34,4 @@
 ## 栈
 
 - [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)

Original file line number	Diff line number	Diff line change
`@@ -34,3 +34,4 @@`
`34`	`34`	`## 栈`
`35`	`35`
`36`	`36`	`- [20. 有效的括号](https://github.com/Geekhyt/javascript-leetcode/issues/21)`
	`37`	`+- [84. 柱状图中最大的矩形](https://github.com/Geekhyt/javascript-leetcode/issues/22)`