pnpm functionality is not documented

[koodistrom]

Hello,

I had to switch package manager from yarn to pnpm in one of my projects and it was bit confusing:

• pnpm is mentioned as supported in the README but then in the usage documentation: https://github.com/node-gradle/gradle-node-plugin/blob/main/docs/usage.md it is not mentioned
• I assumed pnpm would work like yarn as they are both external package managers, but they don't: yarn is always downloaded regardless if download is true or false, but pnpm is downloaded only if download=true

Small thing but bit confusing. I would send a pr but I am not sure what is the correct fix here, just documenting the pnpm functionality or aligning yarn and pnpm functionality (and if so should they respect the download setting or not)

Anyway thanks for an awesome opensource project!

[deepy]

Happy to hear you like it!

So currently yarn is the outlier, both in terms of it being an old version (1.x) and that it's always being installed
Everything is generally modeller and generally works the same as the Npm stuff, except Yarn which is always installed 😀

I'm a bit slow at responding to PRs for code changes, but both those and documentation updates are greatly appreciated
With that said, getting Yarn to behave like the others is a bit of a bigger undertaking and the test suite relies on a lot of end-to-end stuff and is quite unpleasant to run on a computer without lots of cores (and fast internet) so I think documentation is probably the best way to contribute :-)