Organize supported Ubuntu versions

[asfimport]

https://arrow.apache.org/install/ doest not describe proper supported Ubuntu versions like https://github.com/red-data-tools/packages.red-data-tools.org#supported-platforms

Reporter: okkez / @okkez
Assignee: okkez / @okkez

PRs and other links:

• GitHub Pull Request #2307

_{Note: This issue was originally created as ARROW-2897. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 2307
#2307