[docs] add local persistent microvm usage

doc/src/anleitung/microvm.md

@@ -12,14 +12,44 @@ Use durruti as orientation:
 "10.0.0.5" is the IP assigned to its tap interface.  
 
 ### Testing MicroVMs locally
-MicroVMs can be built and run easily on your local host.
-For durruti this is done by:
+MicroVMs can be built and run easily on your local host, but they are not persistent!
+For durruti for example this is done by:
 ``` bash
-sudo nix run .\#nixosConfigurations.durruti.config.microvm.declaredRunner
+nix run .\#durruti-vm
+```
+
+### Testing persistent microvms
+In order to test persistent microvms locally we need to create them using the ```microvm``` command.  
+This is necessary to be able to mount persistent /etc and /var volumes on those hosts.  
+Do the following:
+
+```bash
+# go into our repo and start the default dev shell (or us direnv)
+nix develop .#
+
+# create a microvm on your host (on the example of durruti)
+sudo microvm -c durruti -f git+file:///home/username/path/to/infrastructure/repo
+
+# start the vm
+sudo systemctl start microvm@durruti.serivce
+
+# this may fail, if so we most probably need to create /var /etc manually, then restart
+sudo mkdir /var/lib/microvms/durruti/{var, etc}
+
+# now you can for example get the rsa host key from /var/lib/microvms/durruti/etc/ssh/
+
+# alternatively u can run the vm in interactive mode (maybe stop the microvm@durruti.service first)
+microvm -r durruti
+
+# after u made changes to the microvm update and restart the vm 
+microvm -uR durruti
+
+# deleting the vm again:
+sudo systemctl stop microvm@durruti.service
+sudo systemctl stop microvm-virtiofsd@durruti.service
+sudo rm -rf /var/lib/microvms/durruti
 ```
 
-It seems to be necessary to run this as root so that the according tap interface can be created.
-To be able to ping the VM or give Internet Access to the VM your host needs to be setup as described below.
 
 ### Host Setup