GitHub PR template: JIRA is sometimes optional (apache#881)

Co-authored-by: Christine Poerschke <[email protected]>

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,7 +7,8 @@ Before creating a pull request, please file an issue in the ASF Jira system for
 
 * https://issues.apache.org/jira/projects/SOLR
 
-You will need to create an account in Jira in order to create an issue.
+For something minor (i.e. that wouldn't be worth putting in release notes), you can skip JIRA. 
+To create a Jira issue, you will need to create an account there first.
 
 The title of the PR should reference the Jira issue number in the form: