Documentation reorg for v4.6.0

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

userdocs/images/selinux.rst

@@ -0,0 +1,29 @@
+.. _selinux_images:
+
+======================
+SELinux-enabled Images
+======================
+
+Warewulf supports booting SELinux-enabled images, though nodes using SELinux
+must be configured to use tmpfs for their image file system. ("ramfs," often
+used by default, does not support extended file attributes, which are required
+for SELinux context labeling.)
+
+.. code-block:: bash
+
+   wwctl profile set default --root tmpfs
+
+.. note::
+
+   Versions of Warewulf prior to v4.5.8 also required a kernel argument
+   "rootfstype=ramfs" in order for wwinit to copy the node image to tmpfs; but
+   this is no longer required.
+
+Once that is done, enable SELinux in ``/etc/sysconfig/selinux`` and install the
+appropriate packages in the image. `An example`_ of such an image is available
+in the warewulf-node-images repository.
+
+.. _An example: https://github.com/warewulf/warewulf-node-images/tree/main/examples/rockylinux-9-selinux
+
+SELinux requires extended attributes, which aren't supported on a default
+``initrootfs``. Nodes using SELinux should specify ``--root=tmpfs``.