Changelog out of date

[SimJoSt]

The changelog in this repository (https://github.com/nextcloud/ocsms/blob/master/CHANGELOG.md) is only listing versions and their changes up to 1.7.0
Some rudimentary changelog is given in the description of the releases (https://github.com/nextcloud/ocsms/releases).

Preferably the original changelog should be extended with the new releases and changes.
If this is not possible, it should at least be marked as out of date or completely removed, as it could lead to confusion.