In jira-application.properties we have:

jira.releasenotes.templates = releasenotes-text.vm, releasenotes-html.vm
jira.releasenotes.templatenames = Text, Html

One can add new templates by appending to the lists, but:

jira.releasenotes.templates = releasenotes-text.vm, releasenotes-html.vm, myreleasenotes.vm
jira.releasenotes.templatenames = Text, Html, My release notes

doesn't work, because templatenames breaks on commas and spaces, so JIRA would find 5 template names. We should split only on commas.