After preparing the 2020.5.19 release candidate and
reviewing the packages, some changes turned out to be necessary.

Therefore the date was changed to 2020.5.20 with the folowing
fixes:

* cncf.kubernetes.example_dags were hard-coded and added for all
  packagesa and they were removed
* Version suffix is only used to rename the binary packages not for
  the version itself
* Release process description is updated with the release process
* Package version is consistent - leading 0s are skipped in month
  and day