Adding an issue template

[HeyGarrison]

👋 Hey there!

Just saw that y'all didn't have an issue template in place with validations. So I made an issue template that you might be able to copy over and use as your own. You can check it out here:

https://github.com/HeyGarrison/lightning-design-system/blob/main/.github/ISSUE_TEMPLATE/bug_report.yml

FYI - I added a link to y'all's lightning example imported from GitHub into StackBlitz. You can see that here: https://stackblitz.com/fork/github.com/salesforce-ux/design-system-starter-kit