Release CDEvents 1.0

[e-backmark-ericsson]

This issue is to keep track of activities needed to reach the 1.0 release of CDEvents

Those activities include:

• Proper governance for the project in place (https://github.com/cdevents/community/pull/38)
• Aim at having one way and one way only to describe 'things'. One such example is how events are connected/related to each other. With #139 we get two different ways to provide 'links' between events, and since earlier we have an implicit way of relating events through their subject ids.