Add issue template for releasing new docker images
What does this MR do?
Had a discussion with @drewcimino on how we can document the steps to take when releasing a new version.
We think opening an issue every time we need to release a new image can cover for this. Also, it can be beneficial to the wider community as issues labeled release
can be searched. This makes it easier to know whether an image has already been released for a certain version.
This MR adds an issue template for releasing new versions.