update comment

README.md

@@ -28,7 +28,7 @@ snac2nex -s /path/to/snac/storage -t /path/to/nex -u user1 -u user2
           Target directory for public data export
 
   -u, --user <USER>
-          Username to export
+          Username(s) to export
 
   -a, --attachment <ATTACHMENT>
           Include attachment files export

src/config.rs

@@ -11,7 +11,7 @@ pub struct Config {
     #[arg(short, long)]
     pub target: String,
 
-    /// Username to export
+    /// Username(s) to export
     #[arg(short, long)]
     pub user: Vec<String>,