Invoke disk check periodically. (#7374)

Why I did it
Helps with periodic scan of disk for RO state.
If found, this script makes transient fix and raise error message.

files/image_config/monit/conf.d/sonic-host

@@ -31,5 +31,12 @@ check program routeCheck with path "/usr/local/bin/route_check.py"
     every 5 cycles
     if status != 0 for 3 cycle then alert repeat every 1 cycles
 
+# Check if /etc & /home are writable. If not, make them writable.
+# Raise syslog error message, in case of underlying issues
+#
+check program diskCheck with path "/usr/local/bin/disk_check.py"
+    every 5 cycles
+    if status != 0 for 3 cycle then alert repeat every 1 cycles
+
 check program container_checker with path "/usr/bin/container_checker"
     if status != 0 for 5 times within 5 cycles then alert repeat every 1 cycles