fixed docs and added styleguide

Signed-off-by: Christian Rebischke <chris@nullday.de>

README.md

 # arch-boxes
-[![Actions Status](https://github.com/archlinux/arch-boxes/workflows/CI/badge.svg)](https://github.com/archlinux/arch-boxes/actions)
+[![Actions Status](https://github.com/archlinux/arch-boxes/workflows/Github-Actions/badge.svg)](https://github.com/archlinux/arch-boxes/actions)
 
 Arch-boxes provides automated builds of the Arch Linux releases for
 different providers and post-processors. Check the providers or post-processor sections if you want to know

STYLEGUIDE.md

+# Styleguide
+
+## Python
+
+All python scripts must be formatted with `yapf` and checked for errors and pep8 with `flake8`.
+
+## Bash
+
+All shell scripts must be formatted with `shfmt -i2 -ci` and be syntax checked via `shellcheck`.
+
+## Vagrant
+
+Vagrant json configuration has to be checked with `packer validate`.