Improve Automation Template Library - Add an option to add rules into the library, make playground rules exportable

As a rule writer

I want to export a rule from the Automation Playground

So I can use the existing rule as a starting point for my own projects' rules

The automation playground may be found here: https://docs.automationforjira.com/rule-playground

Acceptance Criteria

• Can select one or more rules for export from the playground
• An exported rule's JSON can be imported into another project/Jira instance
• Bonus: documentation for automation provides use case examples, including a downloadable JSON for the explained rule

 
By now, there is only the rules that come by default in Automation for Jira. It would be nice if the users are able to add some new rules in the library.