[docs] Fix release naming (#7032)

- **[docs] Fix release naming**
- **Remove outdated and unmaintained file**

Closes #6998

---------

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

README.md

@@ -40,9 +40,9 @@ curl --proto '=https' --tlsv1.2 -sSf https://raw.githubusercontent.com/paritytec
 <!-- 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)
 
-The Polkadot SDK is released every three months as a `stableYYMMDD` release. They are supported for
+The Polkadot SDK is released every three months as a `stableYYMM` release. They are supported for
 one year with patches. See the next upcoming versions in the [Release
-Registry](https://github.com/paritytech/release-registry/).
+Registry](https://github.com/paritytech/release-registry/) and more docs in [RELEASE.md](./docs/RELEASE.md).
 
 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.

docs/RELEASE.md

@@ -14,7 +14,11 @@ Merging to it is restricted to [Backports](#backports).
 
 We are releasing multiple different things from this repository in one release, but we don't want to use the same
 version for everything. Thus, in the following we explain the versioning story for the crates, node and Westend &
-Rococo. To easily refer to a release, it shall be named by its date in the form `stableYYMMDD`.
+Rococo.
+
+To easily refer to a release, it shall be named by its date in the form `stableYYMM`. Patches to stable releases are
+tagged in the form of `stableYYMM-PATCH`, with `PATCH` ranging from 1 to 99. For example, the fourth patch to
+`stable2409` would be `stable2409-4`.
 
 ## Crate