Installation guide for Gentoo Linux

Yggdrasil has been added to the Gentoo GURU repository (somewhat like
AUR for Gentoo):
https://gitweb.gentoo.org/repo/proj/guru.git/tree/net-p2p/yggdrasil-go

This commit adds a guide for installing Yggdrasil using this repository
on Gentoo.

installation-linux-gentoo.md

@@ -0,0 +1,79 @@
+---
+tags: dontlink
+sitemap: true
+---
+
+# Installing on Gentoo Linux
+
+Yggdrasil is hosted in the Gentoo GURU repository as the
+[net-p2p/yggdrasil-go](https://gitweb.gentoo.org/repo/proj/guru.git/tree/net-p2p/yggdrasil-go)
+package.
+
+## Package install from the GURU repository
+
+The GURU repository has to be enabled using `eselect repository`.
+
+```
+sudo eselect repository enable guru
+```
+
+And then synchronized with `emerge`:
+
+```
+sudo emerge --sync
+```
+
+Now, the `net-p2p/yggdrasil-go` package is masked and marked as unstable using
+the `~amd64` keyword. So we have to unmask it by accepting the keyword, there
+are two alternatives.
+
+1. If `/etc/portage/package.accept_keywords` is a directory:
+
+```
+echo "net-p2p/yggdrasil-go ~amd64" | sudo tee /etc/portage/package.accept_keywords/yggdrasil-go
+```
+
+2. If `/etc/portage/package.accept_keywords` is a file:
+
+```
+echo "net-p2p/yggdrasil-go ~amd64" | sudo tee -a /etc/portage/package.accept_keywords
+```
+
+Now `net-p2p/yggdrasil-go` can be merged and installed with:
+
+```
+sudo emerge --ask net-p2p/yggdrasil-go
+```
+
+And you're good to go!
+
+## Making configuration changes
+
+Modify the `/etc/yggdrasil.conf` file and then either reload the config:
+
+1. OpenRC
+```
+rc-service yggdrasil reload
+```
+
+2. systemd
+```
+systemctl reload yggdrasil
+```
+
+... or restart the Yggdrasil daemon altogether:
+
+1. OpenRC
+```
+rc-service yggdrasil restart
+```
+
+2. systemd
+```
+systemctl restart yggdrasil
+```
+
+## After installation
+
+Read the [Linux platform page](platform-linux.md) page for further
+information about Linux platform support.

installation.md

@@ -10,6 +10,7 @@ Installation guides are available for the following platforms/distributions.
 
 - [Debian, Ubuntu, elementaryOS, Linux Mint and similar](installation-linux-deb.md)
 - [Red Hat Enterprise Linux, Fedora, CentOS and similar](installation-linux-rpm.md)
+- [Gentoo Linux](installation-linux-gentoo.md)
 - [Ubiquiti EdgeOS](installation-linux-edgeos.md)
 - [Manual install or build from source](installation-linux-other.md)