Merge pull request thibmaek#110 from ceclinux/add_gentoo_source

add gentoo image description

Author: thibmaek

README.md

@@ -77,6 +77,7 @@ The complete collection of Raspberry Pi models consist of:
 - [FabScanPi](https://mariolukas.github.io/FabScanPi-Server/) - FabScanPi is an open source 3D laser scanner using the Raspberry Pi Camera Module. ![Supports Raspberry Pi 2+](/media/badges/rpi-2+.png)
 - [Rocket Show](https://rocketshow.net) - Play synced backing tracks, videos and DMX light-sequences live on stage. ![Supports Raspberry Pi 3](/media/badges/rpi-3.png)
 - [SamplerBox](http://www.samplerbox.org/makeitsoftware) - Drop'n'play sampler: drop .WAV samples on the SD card, and play!
+- [Gentoo](https://wiki.gentoo.org/wiki/Raspberry_Pi) - Gentoo Stage 3 tarball for Raspberry Pi.
 
 ## Tools