ArrayList初始化代码JDK版本，说明JDK7和JDK8初始化差异

Update java-learning-website-blog.md

Update java-learning-path-and-methods.md - 错别词语

Update 几道常见的链表算法题.md

Update 事务隔离级别(图文详解).md

Update java线程池学习总结.md

Update java线程池学习总结.md

fix markdown error

fix OSPF error

Update 数据库索引.md to fix markdown errors

Update 万字详解ThreadLocal关键字.md

[F] Missing markdown bold ** symbol in Java基础知识.md

单词修改：Extention ClassLoader => Extension ClassLoader

formation update