PARQUET-1672: [DOC] Fix broken link in README.md (#154)

README.md

@@ -241,7 +241,7 @@ There are many places in the format for compatible extensions:
 
 ## Contributing
 Comment on the issue and/or contact [the parquet-dev mailing list](http://mail-archives.apache.org/mod_mbox/parquet-dev/) with your questions and ideas.
-Changes to this core format definition are proposed and discussed in depth on the mailing list. You may also be interested in contributing to the Parquet-MR subproject, which contains all the Java-side implementation and APIs. See the "How To Contribute" section of the [Parquet-MR project](github.com/apache/parquet-mr)
+Changes to this core format definition are proposed and discussed in depth on the mailing list. You may also be interested in contributing to the Parquet-MR subproject, which contains all the Java-side implementation and APIs. See the "How To Contribute" section of the [Parquet-MR project](https://github.com/apache/parquet-mr#how-to-contribute)
 
 ## Code of Conduct