Add some dates to our complete roadmap items
Add some dates to our complete roadmap items

While it might be clear based on our version number where we are
in our plan/roadmap - I thought it might be good to put dates next
to each milestone.

For v0.1 it was easy, I just picked the date the release was cut.
For "Setup" it was a bit of a guess since its a unclear when we actually
complete ALL of those items. I picked Feb 26th since that was the date
we merged Dan's PR to add a LICENSE doc. It seemed as good of a date as
any - not sure it matters much.

Signed-off-by: Doug Davis <ff3bde741799c0eff815b83a54eda3fc494df54f@us.ibm.com>

cloudevents/spec