Add --host file to restrict fetches

docs/router_backup.1

@@ -8,6 +8,7 @@ ipng-router-backup \- SSH Router Backup Tool
 .RI [ --password " PASSWORD" ]
 .RI [ --key-file " KEYFILE" ]
 .RI [ --port " PORT" ]
+.RI [ --host " HOSTNAME" ]...
 .SH DESCRIPTION
 .B router_backup
 is a tool for backing up router configurations via SSH. It connects to multiple routers defined in a YAML configuration file and executes commands, saving the output to files.
@@ -30,6 +31,9 @@ SSH private key file path
 .BR --port " \fIPORT\fR"
 SSH port number (default: 22)
 .TP
+.BR --host " \fIHOSTNAME\fR"
+Specific host(s) to process (can be repeated, processes all if not specified)
+.TP
 .BR --help
 Show help message
 .SH CONFIGURATION
@@ -81,6 +85,11 @@ Using password authentication:
 .EX
 ipng-router-backup --config config.yaml --password mysecretpass
 .EE
+.TP
+Process specific hosts only:
+.EX
+ipng-router-backup --config config.yaml --host asw100 --host asw120
+.EE
 .SH FILES
 .TP
 .I /etc/ipng-router-backup/config.yaml.example