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.*}

Comienza con la página de documentación de Parquet enlazada en el issue y revisa las referencias a LogicalTypes.md y Encodings.md. Revisa las secciones Types, Data Pages, Extensibility y Nested Encoding en busca de los problemas de renderizado de Markdown indicados. Se considera terminado cuando los enlaces funcionan y las listas y los guiones bajos se renderizan correctamente.

Escrito por el modelo de indexación a partir del texto del issue.