Adding /etc/modprobe.d folder for module configuration (#397)

* Add a /etc/modprobe.d folder

populated using a config USB stick with folder modprobe

* Add the documentation for the modprobe folder

buildroot-external/rootfs-overlay/etc/systemd/system/systemd-modules-load.service.d/hassos.conf

@@ -1,2 +1,2 @@
 [Unit]
-RequiresMountsFor=/etc/modules-load.d
+RequiresMountsFor=/etc/modules-load.d /etc/modprobe.d

buildroot-external/rootfs-overlay/usr/lib/systemd/system/etc-modprobe.d.mount

@@ -0,0 +1,14 @@
+[Unit]
+Description=Kernel persistent modprobe.d
+Requires=mnt-overlay.mount
+After=mnt-overlay.mount
+Before=systemd-modules-load.service hassos-config.service
+
+[Mount]
+What=/mnt/overlay/etc/modprobe.d
+Where=/etc/modprobe.d
+Type=None
+Options=bind
+
+[Install]
+WantedBy=hassos-bind.target

buildroot-external/rootfs-overlay/usr/sbin/hassos-config

@@ -44,12 +44,21 @@ fi
 ##
 # Modules
 if [ -d "${CONFIG_DIR}/modules" ]; then
-    echo "[Info] Update Modules configuration!"
+    echo "[Info] Update Modules autoload!"
 
     rm -rf /etc/modules-load.d/*
     cp -f ${CONFIG_DIR}/modules/* /etc/modules-load.d/
 fi
 
+##
+# Modules configuration
+if [ -d "${CONFIG_DIR}/modprobe" ]; then
+    echo "[Info] Update Modules configuration!"
+
+    rm -rf /etc/modprobe.d/*
+    cp -f ${CONFIG_DIR}/modprobe/* /etc/modprobe.d/
+fi
+
 ##
 # Udev
 if [ -d "${CONFIG_DIR}/udev" ]; then