Documentation and tests for hostlist syntax

Added this to a new top-level page for wwctl

Closes #611

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

userdocs/contents/wwctl.rst

@@ -0,0 +1,33 @@
+============================
+Controlling Warewulf (wwctl)
+============================
+
+Warewulf's command-line interface is based primarily around the
+``wwctl`` command. This command has sub-commands for each major
+component of Warewulf's functionality.
+
+* ``configure`` configures external services that Warewulf depends on
+* ``container`` configures containers (node images)
+* ``kernel`` configures override kernels
+* ``node`` manages nodes in the cluster
+* ``profiles`` defines configuration which can be applied to multiple
+  nodes
+* ``overlays`` manages nodes
+* ``power`` turns nodes on and off
+* ``ssh`` provides basic parallel ssh functionality
+
+All of these subcommands (and their respective sub-subcommands) have
+built-in help with either ``wwctl help`` or ``--help``.
+
+Hostlists
+=========
+
+Many of the commands (e.g., ``wwctl node list`` support a "hostlist"
+syntax for referring to multiple nodes at once. Hostlist expressions
+support both ranges and comma-separated numerical lists.
+
+For example:
+
+* ``node[1-2]`` expands to ``node1 node2``
+* ``node[1,3]`` expands to ``node1 node3``
+* ``node[1,5-6]`` expands to ``node1 node5 node6``

userdocs/index.rst

@@ -14,6 +14,7 @@ Welcome to the Warewulf User Guide!
    Control Server Setup <contents/setup>
    Warewulf Installation <contents/installation>
    Warewulf Configuration <contents/configuration>
+   Controlling Warewulf (wwctl) <contents/wwctl>
    Warewulf Initialization <contents/initialization>
    Container Management <contents/containers>
    Kernel Management <contents/kernel>