Add note about hostname conventions

Author: JohnGarbutt

README.md

@@ -76,6 +76,10 @@ To deploy, create a playbook which looks like this:
           openhpc_packages: []
     ...
 
+Note that the "compute" of the openhpc_slurm_partition name and the
+openhpc_cluster_name are used to generate the compute node in the
+slurm config of openhpc-compute-[0:7]. Your inventory entries
+for that partition must match that convention.
 
 To drain nodes, for example, before scaling down the cluster to 6 nodes: