Docs warning against npm, still relevant?

[chrisbrainerd]

There's a line in the contributing docs:

Note, we use yarn because npm has unfortunately become unreliable. Get it here.

Is there any reason to keep this here? #2081 is the PR from when it was added - seems like the only gripe was over lockfiles which are plenty standard and stable these days.

[layershifter]

#3816 was merged, closing.