docs: add setup scripts to README

README.org

 for i in $(docker ps -a | grep Exited | grep ogc | cut -f 1 -d ' '); do docker rm $i; done;
 #+end_example
 
+If it's a new installation, run setup scripts:
+#+begin_example
+./set_arch.sh amd64
+./setup.sh # -y for default values
+#+end_example
+
 Optionally build:
 
 #+begin_example