Update README.md to move the PSVM link under a "Tooling" section unde…

…r the "Releases" section

This update implements the suggestion from @kianenigma mentioned in paritytech#4718 (comment)

README.md

@@ -50,6 +50,10 @@ non-breaking features on a **two week** cadence.
 `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`.
 
+## 🛠️ Tooling
+
+[Polkadot SDK Version Manager](https://github.com/paritytech/psvm) - A simple tool to manage and update the Polkadot SDK dependencies in any Cargo.toml file. It will automatically update the Polkadot SDK dependencies to their correct crates.io version.
+
 ## 🔐 Security
 
 The security policy and procedures can be found in