docs/contributing: Recommend Corepack over direct pnpm (#1969)

Author: auscompgeek

docs/contributing/CONTRIBUTING.md

@@ -9,7 +9,7 @@ extension](#running--testing-extension-locally). You may also find the [VSCode A
 
 - [Git](https://git-scm.com/)
 - [Node.js](https://nodejs.org/en/)
-- [pnpm](https://pnpm.io/installation)
+- [Corepack](https://nodejs.org/api/corepack.html) or [pnpm](https://pnpm.io/installation)
 - [VSCode](https://code.visualstudio.com/); minimum version for local development is 1.72.0 in order to support settings profiles for sandboxed development. Please file an issue if that is a problem.
 
 ### Steps