Clarify machine documentation (#3073)

This PR makes it clear that VMs are running on bare metal machines (not
in addition to).

Also simplified a sentence in machine usage guide.

pages/docs/compute-cluster/machine-usage-guide.mdx

@@ -10,17 +10,15 @@ There are two main types of machines in the cluster: [general-use machines](/mac
 ### General-Use Machines
 
 General-use machines are meant for interactive use and are shared among all users in the cluster.
-Additionally, SLURM compute nodes are accessible through general use machines marked as SLURM login
-nodes (`SL`) in the [machine list](/machines#general-use-machines).
+Additionally, general-use machines marked as SLURM login nodes (`SL`) in the [machine list](/machines#general-use-machines)
+can be used to submit jobs to the [SLURM cluster](./slurm).
 
 Instructions for accessing our general-use machines can be found in our [SSH documentation](./ssh).
 
 ### SLURM Compute Nodes
 
 Simple Linux Utility for Resource Management (SLURM) is an open-source job scheduler that allocates resources to jobs on a cluster of computers.
-It is widely used in HPC[^hpc] environments.
-
-SLURM machines can be used for both interactive development as well as job scheduling. They provide fair, stable, and secure access to WATcloud's most precious resources (eg. GPUs).
+It is widely used in HPC[^hpc] environments to provide a fair and efficient way to run jobs on a shared cluster.
 
 Instructions for accessing our SLURM cluster can be found in our [SLURM documentation](./slurm).
 

pages/machines.mdx

@@ -7,8 +7,8 @@ import { pluralizeWithCount } from '@/lib/utils'
 There are
 [{pluralizeWithCount(machineInfo.machines['slurm_compute_nodes'].length, "SLURM compute node")}](#slurm-compute-nodes)
 , [{pluralizeWithCount(machineInfo.machines['dev_vms'].length, "general-use machine")}](#general-use-machines)
-, [{pluralizeWithCount(machineInfo.machines['bastions'].length, "bastion host")}](#bastion-hosts)
-, and [{pluralizeWithCount(machineInfo.machines['bare_metals'].length, "bare-metal machine")}](#bare-metal-machines)
+, and [{pluralizeWithCount(machineInfo.machines['bastions'].length, "bastion host")}](#bastion-hosts)
+hosted on [{pluralizeWithCount(machineInfo.machines['bare_metals'].length, "bare-metal machine")}](#bare-metal-machines)
 in the cluster.
 
 ### SLURM Compute Nodes