docs: add more docs to command

cmd/celestia-appd/cmd/addrbook.go

@@ -20,7 +20,10 @@ func addrbookCommand() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "addrbook peers.txt addrbook.json",
 		Short: "Convert a list of peers into an address book",
-		Args:  cobra.ExactArgs(2),
+		Long: "Convert a list of peers into an address book.\n" +
+			"The first argument (peers.txt) should contain a new line separated list of peers. The format for a peer is `id@ip:port` or `id@domain:port`.\n" +
+			"The second argument (addrbook.json) should be the output filename. The address book is saved to the output file in JSON format.\n",
+		Args: cobra.ExactArgs(2),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			inputFile := args[0]
 			outputFile := args[1]