The bare bones reporting feature of Jira can be used to generate product release notes, and here are the steps:
Pick Projects from navigation bar
Select your project (either from the list, or navigate to the project from View all projects)
Select Versions (Releases in Jira) in the project sidebar
Select the Version (or release) for which release notes are to be generated
Select Release Notes and click the ‘Configure Release Notes‘ link
Pick the right version from ‘Please select version‘ drop-down
Select the format in which release notes are required from the ‘Please select style‘ drop-down
Click the ‘Create‘ button to generate notes based on a specific template in a specific format.
The display results can be copied and pasted in another document, or can be exported into the version desired.