document NFS server setup

admin-guide/configuration/nfs_server.md

@@ -8,6 +8,8 @@ To enable the NFS server, set `base::enable_nfs_server` accordingly in Hiera:
 base::enable_nfs_server: true
 ```
 
+## Exports
+
 Then the exports go below `nfs_server::exports`:
 ```
   '/home/meg/dcbboot':
@@ -20,10 +22,12 @@ Then the exports go below `nfs_server::exports`:
       - hosts: 'sf-export-1[2-3]-100g'
         options: 'rw,async,no_root_squash'
 ```
-For each directory you want to export place its path as key. Below you can set the global options in `options` and a list of client specific access restrictions and options below `clients`.
+For each directory you want to export place its path as key to `nfs_server::exports`. Below you can set the global options in `options` and a list of client specific access restrictions and options below `clients`.
 
 Possible client host definitions and options you find in [`exports(5)`](https://man7.org/linux/man-pages/man5/exports.5.html).
 
+## Non-Standard NFS Server Configuration
+
 If you wish non-standard configuration in `/etc/nfs.conf`, you may set it in Hiera with key `nfs_server::nfs_conf`:
 
 ```
@@ -35,4 +39,12 @@ nfs_server::nfs_conf:
 ```
 For more details see [`nfs.conf(5)`](https://man7.org/linux/man-pages/man5/nfs.conf.5.html)
 
+## Kerberos
 If you need/want to provide Kerberos authenticated access, please speak to the Core Linux Team as we need to add support for it to Puppet first.
+
+## Exporting from GPFS
+If you want to export data backed on GPFS, please set
+```
+nfs_server::after_gpfs: true
+```
+to start the NFS server only after GPFS is ready.