[hive-site] Add Issues Mailing List

Hi Hive dev, I found we missed the Issues Mailing List in hive-site. I think it is necessary to add it, so some people can subscribe & receive Hive JIRA notifications. I submitted a PR[1] to add it. Please check if it is reasonable. BTW, i also removed the outdated incubat

[Discuss] Should we set the Security Level label default value of newly created JIRA to None?

Hi folks, At present, the Security Level label default value of newly created JIRA is Public, which means that all of JIRA users can see the JIRA details if they login in the JIRA account. However, I think many other new Hive users may not have the JIRA account, and the