REUSE: (CC0-1.0) module descriptors and configuration files

In spite of there being considerable documentation sometimes in the
config file, we go with CC0 because we don't want the notion of
'derived work' of a config file.

The example `settings.conf` is also CC0. Add some docs to
it while we're at it.

settings.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Configuration file for Calamares
-# Syntax is YAML 1.2
+# 
+# This is the top-level configuration file for Calamares.
+# It specifies what modules will be used, as well as some
+# overall characteristics -- is this a setup program, or
+# an installer. More specific configuration is devolved
+# to the branding file (for the UI) and the individual
+# module configuration files (for functionality).
 ---
 # Modules can be job modules (with different interfaces) and QtWidgets view
 # modules. They could all be placed in a number of different paths.

src/modules/bootloader/bootloader.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Bootloader configuration. The bootloader is installed to allow
 # the system to start (and pick one of the installed operating
 # systems to run).

src/modules/bootloader/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 ---
 type:       "job"
 interface:  "python"

src/modules/contextualprocess/contextualprocess.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Configuration for the contextual process job.
 #
 # Contextual processes are based on **global** configuration values.

src/modules/displaymanager/displaymanager.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Configure one or more display managers (e.g. SDDM)
 # with a "best effort" approach.
 #

src/modules/displaymanager/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 ---
 type:       "job"
 name:       "displaymanager"

src/modules/dracut/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 ---
 type:       "job"
 name:       "dracut"

src/modules/dummycpp/dummycpp.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # This is a dummy (example) module for C++ Jobs.
 #
 # The code is the documentation for the configuration file.

src/modules/dummycpp/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 # Module metadata file for dummycpp job
 #
 # The metadata for C++ (qtplugin) plugins is almost never interesting:

src/modules/dummyprocess/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 # Module metadata file for dummy process jobmodule
 # Syntax is YAML 1.2
 ---

src/modules/dummypython/dummypython.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # This is a dummy (example) module for a Python Job Module.
 #
 # The code is the documentation for the configuration file.

src/modules/dummypython/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 # Module metadata file for dummy python jobmodule
 # Syntax is YAML 1.2
 ---

src/modules/dummypythonqt/dummypythonqt.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # This is a dummy (example) module for PythonQt.
 #
 # The code is the documentation for the configuration file.

src/modules/dummypythonqt/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 # Module metadata file for dummy pythonqt jobmodule
 # Syntax is YAML 1.2
 ---

src/modules/finished/finished.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Configuration for the "finished" page, which is usually shown only at
 # the end of the installation (successful or not).
 ---

src/modules/fsresizer/fsresizer.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Module that resizes a single FS to fill the entire (rest) of
 # a device. This is used in OEM situations where an image is
 # flashed onto an SD card (or similar) and used to boot a device,

src/modules/fstab/fstab.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Creates /etc/fstab and /etc/crypttab in the target system.
 # Also creates mount points for all the filesystems.
 #

src/modules/fstab/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 ---
 type:       "job"
 name:       "fstab"

src/modules/grubcfg/grubcfg.conf

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
+#
 # Create, overwrite or update /etc/default/grub in the target system.
 #
 # Write lines to /etc/default/grub (in the target system) based

src/modules/grubcfg/module.desc

+# SPDX-FileCopyrightText: no
+# SPDX-License-Identifier: CC0-1.0
 ---
 type:       "job"
 name:       "grubcfg"