Documentation reorg for v4.6.0

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

userdocs/images/syncuser.rst

@@ -0,0 +1,30 @@
+========
+Syncuser
+========
+
+Warewulf can optionally synchronize UIDs and GIDs from the Warewulf server to an
+image. This can be particularly useful when there is no central directory (e.g.,
+an LDAP server).
+
+.. note::
+ 
+   Some system services (notably "munge") require a user to have the same UID across all nodes.
+
+Combined with the "syncuser" overlay, Warewulf syncuser also supports defining
+local users on the Warewulf server for synchronization to cluster nodes.
+
+If there is mismatch between the server and the image, the import command will
+generate a warning.
+
+Syncuser may be invoked during image import, exec, shell, or build.
+
+.. code-block:: console
+
+   # wwctl image import --syncuser docker://ghcr.io/warewulf/warewulf-rockylinux:9 rockylinux-9
+   # wwctl image exec --syncuser rockylinux-9 -- /usr/bin/echo "Hello, world!"
+   # wwctl image shell --syncuser rockylinux-9
+   # wwctl image build --syncuser rockylinux-9
+   # wwctl image syncuser rockylinux-9
+
+After syncuser, ``/etc/passwd`` and ``/etc/group`` in the image are updated, and
+permissions on files belonging to these UIDs and GIDs are updated to match.