The SFTP page said `--dump-auth`, which no longer exists: it became a
value of `--dump`, so the docs asked for a flag rclone would reject.
The same line, and a line in the Swift troubleshooting section, also
used `--dump-headers` and `--dump-bodies`. Those still parse, but
SetFlags logs "--dump-headers is obsolete - please use --dump headers
instead", so the docs were steering readers onto a deprecated form.
The generated flag listings in docs/content/flags.md and
docs/content/commands/rclone.md are left alone: those flags do still
exist, so `--help` output should keep showing them.
