Broken links and formatting problems in Parquet documentation

The links to LogicalTypes.md and Encodings.md in [the Parquet documentation](http://parquet.apache.org/documentation/latest/) are broken. That page also has what appear to be some Markdown formatting issues:
- multiple lists are rendering incorrectly: the list of types under the "Types" header, the list of data under the "Data Pages" header, and the list of extension points under the "Extensibility" header
- some underscores that should be escaped are instead rendering as italics - see the last line under the "Nested Encoding" header

**Reporter**: [Roland Crosby](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=rolandcrosby)

_{**Note**: *This issue was originally created as [PARQUET-1161](https://issues.apache.org/jira/browse/PARQUET-1161). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

从 issue 中链接的 Parquet 文档页面开始，检查对 LogicalTypes.md 和 Encodings.md 的引用。检查 Types、Data Pages、Extensibility 和 Nested Encoding 部分，查找报告的 Markdown 渲染问题。链接能够正常工作，并且列表和下划线能够正确渲染，即表示完成。

由索引模型根据 Issue 内容生成。