update info how to create new packages_misc repo

admin-guide/custom_repositories.md

@@ -78,12 +78,16 @@ The access control is done by a Unix group usually named `unx-<something>_adm` (
 The `packages_misc` share is only root writeable from lx-sync-01.psi.ch. Therefore the initial setup needs to be done there.
 
 Creation of a new repo (on lx-sync-01 in `/packages_misc`):
-```
+```bash
 cd /packages_misc
 mkdir <reponame>
-chgrp 35588 <reponame>  ## We need to use the numeric group id here as lx-sync is not directly connected to AD
+chgrp 35593 <reponame>  ## We need to use the numeric group id here as lx-sync is not directly connected to AD
 chmod g+w <reponame>
 chmod g+s <reponame>
+
+# set NFS4 ACL to ensure the group can always write
+# ensure that you repace the id of the group !!!
+nfs4_setfacl -a A:dfg:35593:RWX /modules/test
 ```
 
 To sync the repo and make it available there needs to be a sync config added to https://gitea.psi.ch/lx/rpm-repo-utils