Current documentation on updating Jira - https://confluence.atlassian.com/adminjiraserver/upgrading-jira-applications-938846936.html
has the methods users can follow to update Jira.

In this document, the last method has the following phrase:

Low – Medium

If you use Jira in a non-mission critical environment, depending on your specific installation details, you use either the installer (no downtime) or manual method to upgrade.

This implies that using the installer (bin/exe) does not have downtime for Jira.  This is just flat out incorrect.  In order to update Jira in this method, the java process has to be stopped on the system at some point in order for jira/java/tomcat and lots of other files on the system to be updated.  This phrase should be removed from this specific section because it causes confusion for customers and sets an incorrect expectation about doing the upgrade for Jira.

Other versions of this document should also be updated with this change: https://confluence.atlassian.com/display/ADMINJIRASERVER079/Upgrading+JIRA+applications etc