Link are Broken in README.md

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Record conversion API and Hadoop API links are broken in README.md

Reporter: nihed mbarek / @nihed
Assignee: nihed mbarek / @nihed

_{Note: This issue was originally created as PARQUET-663. Please see the migration documentation for further details.}

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nihed mbarek / @nihed:
PR #350

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Ryan Blue / @rdblue:
Merged. Thanks for contributing, @nihed!