hwdb.d: update/expand boilerplate on various hwdb files

We don't want to encourage people to copy the whole files. The
boilerplate text that recommends an override file rather than a
full copy appeared first in 0213a26f65,
but was added in other places in 57bb707d48.

Directly inspired by 951e8cb060, but
the wrong boilerplate was added in other places too.

hwdb.d/70-av-production.hwdb

@@ -3,13 +3,25 @@
 # Database for AV production controllers that should be accessible to the seat owner.
 #
 # This covers DJ tables, music-oriented key pads, and streaming-oriented key pads
-# such as Elgato Stream Deck
+# such as Elgato Stream Deck.
 #
-# To add local entries, copy this file to
-#   /etc/udev/hwdb.d/
+# The lookup keys are $MODALIAS strings, see udev's hwdb builtin.
+#
+# To add local entries, create a new file
+#   /etc/udev/hwdb.d/71-av-production-local.hwdb
 # and add your rules there. To load the new rules execute (as root):
 #   systemd-hwdb update
-#   udevadm trigger
+#   udevadm trigger /dev/…
+#
+# If your changes are generally applicable, send them as a pull request to
+#   https://github.com/systemd/systemd
+# or create a bug report on https://github.com/systemd/systemd/issues and
+# include your new rules, a description of the device, and the output of
+#   udevadm info
+# for the device.
+#
+# Allowed properties are:
+#   ID_AV_PRODUCTION_CONTROLLER=1
 
 ################
 # Ableton

hwdb.d/70-hardware-wallets.hwdb

@@ -1,12 +1,24 @@
 # This file is part of systemd.
 #
 # Database for Hardware Wallets that should be accessible to the seat owner.
-##
-# To add local entries, copy this file to
-#   /etc/udev/hwdb.d/
+#
+# The lookup keys are $MODALIAS strings, see udev's hwdb builtin.
+#
+# To add local entries, create a new file
+#   /etc/udev/hwdb.d/71-hardware-wallets-local.hwdb
 # and add your rules there. To load the new rules execute (as root):
 #   systemd-hwdb update
-#   udevadm trigger
+#   udevadm trigger /dev/…
+#
+# If your changes are generally applicable, send them as a pull request to
+#   https://github.com/systemd/systemd
+# or create a bug report on https://github.com/systemd/systemd/issues and
+# include your new rules, a description of the device, and the output of
+#   udevadm info
+# for the device.
+#
+# Allowed properties are:
+#   ID_HARDWARE_WALLET=1
 
 ################
 # Trezor Hardware Wallets

hwdb.d/70-lights.hwdb

@@ -1,14 +1,26 @@
 # This file is part of systemd.
 #
-# Database for remote controllable lights that should be accessible to the seat owner,
-# such as Bluetooth or USB lights that are used in conjuction with the computer like
-# streaming lights.
+# Database for remote controllable lights that should be accessible to the seat
+# owner, such as Bluetooth or USB lights that are used in conjuction with the
+# computer like streaming lights.
 #
-# To add local entries, copy this file to
-#   /etc/udev/hwdb.d/
+# The lookup keys are $MODALIAS strings, see udev's hwdb builtin.
+#
+# To add local entries, create a new file
+#   /etc/udev/hwdb.d/71-lights-local.hwdb
 # and add your rules there. To load the new rules execute (as root):
 #   systemd-hwdb update
-#   udevadm trigger
+#   udevadm trigger /dev/…
+#
+# If your changes are generally applicable, send them as a pull request to
+#   https://github.com/systemd/systemd
+# or create a bug report on https://github.com/systemd/systemd/issues and
+# include your new rules, a description of the device, and the output of
+#   udevadm info
+# for the device.
+#
+# Allowed properties are:
+#   ID_AV_LIGHTS=1
 
 ################
 # Logitech

hwdb.d/70-software-radio.hwdb

@@ -1,12 +1,25 @@
 # This file is part of systemd.
 #
-# Database for software-defined radio devices that should be accessible to the seat owner.
+# Database for software-defined radio devices that should be accessible to the
+# seat owner.
 #
-# To add local entries, copy this file to
-#   /etc/udev/hwdb.d/
+# The lookup keys are $MODALIAS strings, see udev's hwdb builtin.
+#
+# To add local entries, create a new file
+#   /etc/udev/hwdb.d/71-software-radio-local.hwdb
 # and add your rules there. To load the new rules execute (as root):
 #   systemd-hwdb update
-#   udevadm trigger
+#   udevadm trigger /dev/…
+#
+# If your changes are generally applicable, send them as a pull request to
+#   https://github.com/systemd/systemd
+# or create a bug report on https://github.com/systemd/systemd/issues and
+# include your new rules, a description of the device, and the output of
+#   udevadm info
+# for the device.
+#
+# Allowed properties are:
+#   ID_SOFTWARE_RADIO=1
 
 ################
 # Nuand

hwdb.d/70-sound-card.hwdb

@@ -1,12 +1,24 @@
 # This file is part of systemd.
 #
-# Database of sound hardware that gets misdetected
+# Database of sound hardware that gets misdetected.
 #
-# To add local entries, copy this file to
-#   /etc/udev/hwdb.d/
+# The lookup keys are $MODALIAS strings, see udev's hwdb builtin.
+#
+# To add local entries, create a new file
+#   /etc/udev/hwdb.d/71-sound-card-local.hwdb
 # and add your rules there. To load the new rules execute (as root):
 #   systemd-hwdb update
-#   udevadm trigger
+#   udevadm trigger /dev/…
+#
+# If your changes are generally applicable, send them as a pull request to
+#   https://github.com/systemd/systemd
+# or create a bug report on https://github.com/systemd/systemd/issues and
+# include your new rules, a description of the device, and the output of
+#   udevadm info
+# for the device.
+#
+# Allowed properties are:
+#   SOUND_FORM_FACTOR
 
 ###########################################################
 # Corsair