fix errors in README.md

README.md

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 ## Contents
 
-* [Introduction](#Introduction)
-* [Why Writing Nasal Interpreter](#Why-Writing-Nasal-Interpreter)
-* [Compile](#How-to-Compile)
-* [Usage](#How-to-Use)
-* [Parser](#Parser)
-  * [v1.0](#Version-1.0-parser-(last-update-2019/10/14))
-* [Abstract Syntax Tree](#Abstract-Syntax-Tree)
-  * [v1.2](#Version-1.2-ast-(last-update-2019/10/31))
-  * [v2.0](#Version-2.0-ast-(last-update-2020/8/31))
-  * [v3.0](#Version-3.0-ast-(last-update-2020/10/23))
-  * [v5.0](#Version-5.0-ast-(last-update-2021/3/7))
-* [Bytecode VM](#Bytecode-Virtual-Machine)
-  * [v4.0](#Version-4.0-vm-(last-update-2020/12/17))
-  * [v5.0](#Version-5.0-vm-(last-update-2021/3/7))
-  * [v6.0](#Version-6.0-vm-(last-update-2021/6/1))
-  * [v6.5](#Version-6.5-vm-(last-update-2021/6/24))
-  * [v7.0](#Version-7.0-vm-(last-update-2021/10/8))
-  * [v8.0](#Version-8.0-vm-(latest))
-* [Benchmark](#Benchmark)
-  * [v6.5 (i5-8250U windows 10)](#Version-6.5-(i5-8250U-windows10-2021/6/19))
-  * [v6.5 (i5-8250U ubuntu-WSL)](#Version-7.0-(i5-8250U-ubuntu-WSL-on-windows10-2021/6/29))
-* [Tutorial](#Simple-Tutorial)
-  * [basic value type](#__Basic-Value-Type__)
-  * [operators](#__Operators__)
-  * [definition](#__Definition__)
-  * [multi-assignment](#__Multi-Assignment__)
-  * [conditional expression](#__Conditional-Expression__)
-  * [loop](#__Loop__)
-  * [subvec](#__Subvec__)
-  * [special function call](#__Special-Function-Call__)
-  * [lambda](#__Lambda__)
-  * [closure](#__Closure__)
-  * [trait](#__Trait__)
-  * [native functions](#__Native-Functions__)
-  * [modules](#__Modules(This-is-for-library-developers)__)
-* [Difference](#Difference-Between-Andy's-Nasal-Interpreter-and-This-Interpreter)
-* [Trace Back Info](#Trace-Back-Info)
-* [Debugger](#Debugger)
+* [Introduction](#introduction)
+* [Why Writing Nasal Interpreter](#why-writing-nasal-interpreter)
+* [Compile](#how-to-compile)
+* [Usage](#how-to-use)
+* [Parser](#parser)
+  * [v1.0](#version-10-parser-last-update-20191014)
+* [Abstract Syntax Tree](#abstract-syntax-tree)
+  * [v1.2](#version-12-ast-last-update-20191031)
+  * [v2.0](#version-20-ast-last-update-2020831)
+  * [v3.0](#version-30-ast-last-update-20201023)
+  * [v5.0](#version-50-ast-last-update-202137)
+* [Bytecode VM](#bytecode-virtual-machine)
+  * [v4.0](#version-40-vm-last-update-20201217)
+  * [v5.0](#version-50-vm-last-update-202137)
+  * [v6.0](#version-60-vm-last-update-202161)
+  * [v6.5](#version-65-vm-last-update-2021624)
+  * [v7.0](#version-70-vm-last-update-2021108)
+  * [v8.0](#version-80-vm-latest)
+* [Benchmark](#benchmark)
+  * [v6.5 (i5-8250U windows 10)](#version-65-i5-8250u-windows10-2021619)
+  * [v6.5 (i5-8250U ubuntu-WSL)](#version-70-i5-8250u-ubuntu-wsl-on-windows10-2021629)
+* [Tutorial](#simple-tutorial)
+  * [basic value type](#basic-value-type)
+  * [operators](#operators)
+  * [definition](#definition)
+  * [multi-assignment](#multi-assignment)
+  * [conditional expression](#conditional-expression)
+  * [loop](#loop)
+  * [subvec](#subvec)
+  * [special function call](#special-function-call)
+  * [lambda](#lambda)
+  * [closure](#closure)
+  * [trait](#trait)
+  * [native functions](#native-functions)
+  * [modules](#modulesthis-is-for-library-developers)
+* [Difference](#difference-between-andys-nasal-interpreter-and-this-interpreter)
+* [Trace Back Info](#trace-back-info)
+* [Debugger](#debugger)
 
 ## Introduction