Remove --filter warning with install

[Mister-Hope]

Related:

• pnpm install --filter (to install dependencies only for selected workspace projects) not working with dedupe-peer-dependents set to true pnpm#6300
• https://pnpm.io/cli/install#--filter-package_selector

If I am understanding everything correct, this is no longer needed in v9.5.0+, so we could remove it in docs folder now as we are targeting v10 now, and every future version should get rid of it.

[Mister-Hope]

@zkochan can you leave a msg on this?

I can create a or for this if you think this is fine.