feat: add comment to config file

cmd/httpd/config.example.yaml

@@ -1,22 +1,38 @@
+# domain used by user interface
 domain: http://127.0.0.1:8080
+# http service binding
 listen: 127.0.0.1:8080
+# debug port binding
 debug_listen: 127.0.0.1:8081
 
+# database settings, you can use sqlite or mysql (untested)
 database:
  dialect: sqlite
  dsn: ./tapes.db
 
+# usable tape drivers, must have sg device mapping.
+# use `sg_map` command (in sg3_utils package) to get corresponding device with sg device mapping.
 tape_devices:
  - /dev/nst0
 
+# working path settings
 paths:
+ # to save logs and write reports
  work: ./
+ # source in backup job creator
  source: ./
+ # restore job target path
  target: ./
 
+# those scripts interact with external software, you may need to change them for your use cases.
 scripts:
+ # enable hardware encryption on tape driver
  encrypt: ./scripts/encrypt
+ # format ltfs on lto tape, may need to be changed for different ltfs software.
  mkfs: ./scripts/mkfs
+ # mount ltfs to specified path, may need to be changed for different ltfs software.
  mount: ./scripts/mount
+ # umount ltfs path
  umount: ./scripts/umount
+ # read tape barcode for restore jobs
  read_info: ./scripts/readinfo