list-only.d: mention SFTP as supported protocol

Closes #11628

docs/cmdline-opts/list-only.d

@@ -2,10 +2,10 @@ c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 SPDX-License-Identifier: curl
 Long: list-only
 Short: l
-Protocols: FTP POP3
+Protocols: FTP POP3 SFTP
 Help: List only mode
 Added: 4.0
-Category: ftp pop3
+Category: ftp pop3 sftp
 Example: --list-only ftp://example.com/dir/
 See-also: quote request
 Multi: boolean
@@ -20,6 +20,12 @@ the server instead of LIST.
 Note: Some FTP servers list only files in their response to NLST; they do not
 include sub-directories and symbolic links.
 
+(SFTP)
+When listing an SFTP directory, this switch forces a name-only view, one per line.
+This is especially useful if the user wants to machine-parse the contents of an
+SFTP directory since the normal directory view provides more information than just
+file names.
+
 (POP3)
 When retrieving a specific email from POP3, this switch forces a LIST command
 to be performed instead of RETR. This is particularly useful if the user wants