Update Gentoo ebuild location

[myrvogna]

Hello again,

A quick follow‑up to #10, I have contributed the ebuilds to the official Gentoo User Repository GURU and will continue to maintain it there in the future, so it'll be nice to update the link to it. Of course, the same sensible warning still applies, but it should nonetheless be more easily accessible and owing to the nature of the GURU project, somewhat more trustworthy.

Thank you.

[Berulacks]

Cheers, I've updated the link!