Add Gentoo Linux install instructions

[bigfootjon]

Yarn is available on Gentoo's portage package manager (1), and I
have a pending patch to yarn to provide correct install instructions
from within the yarn cli (2).

(1) https://packages.gentoo.org/packages/sys-apps/yarn
(2) yarnpkg/yarn#7123

[DanBuild]

Deploy preview for yarnpkg ready!

Built with commit 3ebedb2

https://deploy-preview-935--yarnpkg.netlify.com

[Haroenv]

looks like we will need a fallback for languages not yet translated here too, like for install-ci

[bigfootjon]

@Haroenv are you referring to the file_exists tag? (added in fe50d77)

[Haroenv]

Yes, it's a bit of a hacky workaround, but is needed because of the i18n implementation

[bigfootjon]

Well the build succeeds now but the deploy preview doesn't show any install instructions. @Haroenv Is this expected?

[Haroenv]

That's not expected, and likely an error in the (fairly hacky) workaround for missing files. Unfortunately I don't really have time to look into this right now

[bigfootjon]

I was able to fix the missing install documentation. Turned out to be a flaw with the implementation of file_exists where it didn't strip trailing whitespace, I've inserted a commit to fix that but if you would rather I can split it out into a separate PR or I can rewrite my changes to match the style of the other use of file_exists (i.e. without whitespace around the file path)

[Haroenv]

Thanks for the effort you put in this!ç

[bigfootjon]

Happy to help!