[DOCS] arborist doesnt mention pnpm and yarn support

[jayvdb]

Is there an existing issue for this?

• I have searched the existing issues

This is a CLI Docs Enhancement, not another kind of Docs Enhancement.

• This is a CLI Docs Enhancement.

Description of Problem

There is one mention of "yarn.lock" at https://www.npmjs.com/package/@npmcli/arborist , and no mention of pnpm.
It appears both yarn and pnpm are supported with copious tests.

Potential Solution

It would be useful for the main arborist description to indicate the level of support these package managers have,
and for more detail to be put into https://github.com/npm/cli/tree/latest/workspaces/arborist/docs describing the details/caveats of the support of each.

Docs URL

No response