Add pm-cpu with intel to the developer's guide

It doesn't make sense to add it to the user's guide yet.

Similarly, it doesn't make sense to add pm-gpu yet because
MPAS compoents don't support it (yet).

docs/developers_guide/machines/index.md

@@ -2,11 +2,11 @@
 
 # Machines
 
-Polaris attempts to be aware of the capabilities of the machine it is running 
-on.  This  is a particular advantage for so-called "supported" machines with a 
-config file defined for them in the `polaris` package.  But even for "unknown" 
-machines,  it is not difficult to set a few config options in your user config 
-file to  describe your machine.  Then, polaris can use this data to make sure 
+Polaris attempts to be aware of the capabilities of the machine it is running
+on.  This  is a particular advantage for so-called "supported" machines with a
+config file defined for them in the `polaris` package.  But even for "unknown"
+machines,  it is not difficult to set a few config options in your user config
+file to  describe your machine.  Then, polaris can use this data to make sure
 test  cases are configured in a way that is appropriate for your machine.
 
 (dev-supported-machines)=
@@ -57,6 +57,8 @@ supported for those configurations with `gnu` compilers.
 | compy        | intel      | impi      | intel-mpi         |
 +--------------+------------+-----------+-------------------+
 | pm-cpu       | gnu        | mpich     | gnu-cray          |
+|              +------------+-----------+-------------------+
+|              | intel      | mpich     | intel-cray        |
 +--------------+------------+-----------+-------------------+
 ```
 
@@ -288,8 +290,8 @@ spack:
       modules: []
       environment: {}
       extra_rpaths: []
-```          
-          
+```
+
 Typically your system will already have compilers if nothing else, and this is
 what we assume here.  Give the appropriate path (replace `/usr` with the
 appropriate path on your system).  We have had better luck with `gcc` than

docs/developers_guide/machines/perlmutter.md

@@ -14,3 +14,18 @@ Then, you can build the MPAS model with
 ```bash
 make [DEBUG=true] gnu-cray
 ```
+
+## pm-cpu, intel
+
+Similarly to `gnu`, for `intel`, if you've set things up right, sourcing the
+load scrip will look something like:
+
+```bash
+source load_dev_polaris_0.1.0-alpha.1_pm-cpu_intel_mpich.sh
+```
+
+To build MPAS components, use:
+
+```bash
+make [DEBUG=true] intel-cray
+```