Update Gentoo instructions

scrcpy is available directly in the distro, drop link to the overlay
(which only contains older versions).

PR #3816 <https://github.com/Genymobile/scrcpy/pull/3816>

Signed-off-by: Romain Vimont <rom@rom1v.com>

doc/linux.md

@@ -9,12 +9,10 @@ Scrcpy is packaged in several distributions and package managers:
  - Debian/Ubuntu: `apt install scrcpy`
  - Arch Linux: `pacman -S scrcpy`
  - Fedora: `dnf copr enable zeno/scrcpy && dnf install scrcpy`
- - Gentoo: [ebuild][ebuild-link] file
+ - Gentoo: `emerge scrcpy`
  - Snap: `snap install scrcpy`
  - … (see [repology](https://repology.org/project/scrcpy/versions))
 
-[ebuild-link]: https://github.com/maggu2810/maggu2810-overlay/tree/master/app-mobilephone/scrcpy
-
 ### Latest version
 
 However, the packaged version is not always the latest release. To install the