|This feature is currently available and you can read about it here : https://confluence.atlassian.com/servicedesk/jira-service-desk-3-7-x-release-notes-934718353.html#JIRAServiceDesk3.7.xreleasenotes-Cannedresponses
I am marking this ticket as resolved.
Jira Service Desk
Agents should have the ability to create a signature for their responses to Service Desk customers to prevent having to copy/paste or type out a signature for each response.
There may be a use case for the ability to set these signatures per agent per service desk, also.