[MJAVADOC-772] Refresh download page

[slawekjaranowski]

Following this checklist to help us incorporate your
contribution quickly and easily:

• Make sure there is a JIRA issue filed
  for the change (usually before you start working on it). Trivial changes like typos do not
  require a JIRA issue. Your pull request should address just this issue, without
  pulling in other changes.
• Each commit in the pull request should have a meaningful subject line and body.
• Format the pull request title like [MJAVADOC-XXX] - Fixes bug in ApproximateQuantiles,
  where you replace MJAVADOC-XXX with the appropriate JIRA issue. Best practice
  is to use the JIRA issue title in the pull request title and in the first line of the
  commit message.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Run mvn clean verify -Prun-its to make sure basic checks pass. A more thorough check will
  be performed on your pull request automatically.

If your pull request is about ~20 lines of code you don't need to sign an
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the Apache License Version 2.0, January 2004
you have to acknowledge this by using the following check-box.

• I hereby declare this contribution to be licensed under the Apache License Version 2.0, January 2004

• In any other case, please file an Apache Individual Contributor License Agreement.