clean up Joule HPC build instructions

* To access Joule2, you will need an NETL HPC account, 

  a yubikey (2FA) and the 

  `HPC client <https://hpc.netl.doe.gov/support/hpc-client/index.html>`_

* These instructions build on the login nodes using `-j8` CPUs. 

  `HPC client. <https://hpc.netl.doe.gov/support/hpc-client/index.html>`_

* These instructions build MFIX-Exa on the login nodes using `-j8` CPUs. 

  You may have to decrease this value if there is high traffic 

  or you may want to increase this value if you are on a compute 

  node interactively. 

* The cmake instructions compile to a `build` directory. 

  The gmake instructions compile to a `exec` directory. 

* For the dependencies, we assume you will set the environment 

  path variables:

* For the dependencies, it is assumed that you have set the 

  following environment variables:

  .. code:: bash

     export CSG_LIB_DIR=$HOME/<path/to/my/csg-lib-install-dir>

     export ASCENT_INSTALL_DIR=$HOME/<path/to/my/ascent-install-dir>

  to a descriptive path that the user has read/write access to. 

  to a path that you have read/write access to. 

  You will need to recall these paths later if you want to build 

  MFIX-Exa with the optional dependencies. 

* After building the `mfix` executable (with cmake), you can 

  build the PIC-to-DEM restarter app by: 

  build the PIC-to-DEM restarter app by executing the following command 

  in the `build` directory

  .. code:: bash

Clone the source code

~~~~~~~~~~~~~~~~~~~~~

Before building the code, first clone the code, checkout the desired branch, 

Before building, first clone the code, checkout the desired branch, 

(the default is develop), update the submodules and create a build directory 

(for cmake).

    module load cuda/11.3

Full builds, i.e., with external dependencies, also require setting 

Full builds that utilize external dependencies, also require setting 

certain environment variables as discussed below. 

Optional build dependencies

---------------------------

The following dependencies will need to be installed prior to following any of the full build instructions above. 

The following dependencies need to be built and installed 

prior to following any of the full build instructions above. 

#. Set environment helpers

#. CSG EB library  (**gmake**) 

   For the gmake instaill instructions you will need to install

   For the gmake install instructions, you need to install

   `libcsgeb` to `$CSG_LIB_DIR` using either cmake or gmake:

   .. tabs::