Update README.md

Author: monw3c

README.md

@@ -29,7 +29,7 @@
 * [序言](manuscript/foreword.md/#foreword) ([Brian Lonsdorf, aka "Prof Frisby"](https://twitter.com/DrBoolean))
 * [前言](manuscript/preface.md/#preface)
 * [章节 1: 为什么要函数式编程?](manuscript/ch1.md/#chapter-1-why-functional-programming)
-* [章节 2: 函数的性质](manuscript/ch2.md/#chapter-2-the-nature-of-functions)
+* [章节 2: 函数的本质](manuscript/ch2.md/#chapter-2-the-nature-of-functions)
 * [章节 3: 管理函数输入](manuscript/ch3.md/#chapter-3-managing-function-inputs)
 * [章节 4: 组合函数](manuscript/ch4.md/#chapter-4-composing-functions)
 * [章节 5: 减少副作用影响](manuscript/ch5.md/#chapter-5-reducing-side-effects)