doc: seastar: fix param refrences
doc: seastar: fix param refrences

Resolves the following warnings:
include/seastar/core/seastar.hh:142: warning: unable to resolve reference to 'net::socket' for \ref command
include/seastar/core/seastar.hh:218: warning: unable to resolve reference to 'path' for \ref command
include/seastar/core/seastar.hh:305: warning: argument 'follow_symlink' of command @param is not found in the argument list of seastar::file_stat(sstring name, follow_symlink fs=follow_symlink::yes)
include/seastar/core/seastar.hh:353: warning: argument 'name' from the argument list of seastar::file_type has multiple @param documentation sections
include/seastar/core/seastar.hh:230: warning: unable to resolve reference to 'file::fsync()' for \ref command

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

scylladb/seastar,avikivity/seastar,avikivity/seastar,cloudius-systems/seastar,scylladb/seastar,dreamsxin/seastar,avikivity/seastar,cloudius-systems/seastar,dreamsxin/seastar,syuu1228/seastar,syuu1228/seastar,cloudius-systems/seastar,dreamsxin/seastar,syuu1228/seastar,scylladb/seastar