README.md: update to zeus

Signed-off-by: Ferry Toth <ftoth@exalondelft.nl>

README.md

@@ -22,11 +22,12 @@ Currently we have Intel's original (factory) firmware: orignal and created four
 * **sumo32** and **sumo64-acpi** based on Yocto Sumo with kernel 4.18
 * **thud** (64 bit) based on Yocto Thud with kernel 5.2.
 * **warrior** (64 bit) based on Yocto Warrior with kernel 5.4. This image now allows building Debian Buster as well.
+* **zeus** (64 bit) based on Yocto Warrior with kernel 5.6. This branch is Work in Progress and preparing for btrfs based images when released.
 
 # What to choose
 
-Yocto Morty and later will build on Ubuntu Artful (17.10) up to at least Disco (19.04).
+Yocto Morty and later will build on Ubuntu Artful (17.10) up to at least Focal (20.04).
 
 Generally **sumo32** will give best results if you rely on MRAA and UPM. If you want highly configurable hardware and don't need MRAA, the **thud** enabled version is best.
 
-**warrior** has a 64 bit kernel because we can, but may be actually slower than the 32bit kernel. **master** will normally have the same as warrior, but 32 bits.
+**zeus** has a 64 bit kernel because we can, but may be actually slower than the 32bit kernel. **master** will normally have the same as warrior, but 32 bits.