This PR adds the badges to the readme to show the info about the current
stable release version and the version and date of the upcoming stable
release. The idea here to give a possibility for people from the outside
to have an overview about the current and upcoming release, until we
have a proper public release calendar.

<img width="1280" alt="Screenshot 2024-08-29 at 14 47 57"
src="https://github.com/user-attachments/assets/8faff023-c4b2-444b-95a3-ce6d106e2a7a">

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Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>