Add badges with the release info to the README.md (#5518)

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">

---------

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

README.md

@@ -38,27 +38,15 @@ curl --proto '=https' --tlsv1.2 -sSf https://raw.githubusercontent.com/paritytec
 
 ## 🚀 Releases
 
-> [!NOTE]
-> Our release process is still Work-In-Progress and may not yet reflect the aspired outline
-> here.
-
-The Polkadot-SDK has two release channels: `stable` and `nightly`. Production software is advised to
-only use `stable`. `nightly` is meant for tinkerers to try out the latest features. The detailed
-release process is described in [RELEASE.md](docs/RELEASE.md).
-
-You can use [`psvm`](https://github.com/paritytech/psvm) to manage your Polkadot-SDK dependency
-versions in downstream projects.
-
-### 😌 Stable
-
-`stable` releases have a support duration of **three months**. In this period, the release will not
-have any breaking changes. It will receive bug fixes, security fixes, performance fixes and new
-non-breaking features on a **two week** cadence.
+<!-- markdownlint-disable-next-line MD013 -->
+![Current Stable Release](https://raw.githubusercontent.com/paritytech/release-registry/main/badges/polkadot-sdk-latest.svg)&nbsp;&nbsp;![Next Stable Release](https://raw.githubusercontent.com/paritytech/release-registry/main/badges/polkadot-sdk-next.svg)
 
-### 🤠 Nightly
+The Polkadot-SDK is released every three months as a `stableYYMMDD` release. They are supported for
+one year with patches. See the next upcoming versions in the [Release
+Registry](https://github.com/paritytech/release-registry/).
 
-`nightly` releases are released every night from the `master` branch, potentially with breaking
-changes. They have pre-release version numbers in the format `major.0.0-nightlyYYMMDD`.
+You can use [`psvm`](https://github.com/paritytech/psvm) to update all dependencies to a specific
+version without needing to manually select the correct version for each crate.
 
 ## 🛠️ Tooling