Add format for versions affected and release link

What does this MR do?

In adding versions affected to a security issue I noticed that people are using different formats across issues.

I added some documentation to the template to standardize around specifying the version and a link to a place where versions can be referenced by date.

However, perhaps other devs have stronger opinions about the format the versions or where to reference the release (I'm mostly looking to standardize but don't have strong opinions on what to standardize on).