Updates URLs to link against the apache user instead of Parquet on github

[asfimport]

Reporter: Ben Pence / @benpence
Assignee: Ben Pence / @benpence

Related issues:

• Update README docs for graduation (is part of)

PRs and other links:

• PR #192

_{Note: This issue was originally created as PARQUET-274. Please see the migration documentation for further details.}

[asfimport]

Ryan Blue / @rdblue:
Merged #192. Thanks for fixing this, Ben!