add doc of v0.3.0

Merge pull request GeneralNewsExtractor#107 from kingname/bugfix

fix htag and title lcm bug

Merge pull request GeneralNewsExtractor#103 from kingname/bugfix

update change log and setup.py

Merge pull request GeneralNewsExtractor#93 from kingname/bugfix

移除 footer 标签

Merge pull request GeneralNewsExtractor#88 from kingname/develop

useless_attr 现在必须完全匹配才会移除节点

Merge pull request GeneralNewsExtractor#86 from kingname/develop

自动提取新闻列表页

Merge pull request GeneralNewsExtractor#84 from kingname/develop

修复提取标签中的文本时，只能提取最后一个节点的问题

Merge pull request GeneralNewsExtractor#83 from kingname/develop

大幅度提升提取速度

Merge pull request GeneralNewsExtractor#81 from kingname/develop

更新版本号

Merge pull request GeneralNewsExtractor#71 from kingname/develop

⚙️修复由于预处理导致用户自定义 XPath 无效的问题