man/io_uring_register_files.3: fix grammatical error
@@ -44,6 +44,7 @@ On success
.BR io_uring_register_files (3)
and
.BR io_uring_register_files_sparse (3)
-returns 0. On failure it returns -errno.
+return 0. On failure they return
+.B -errno.
.SH SEE ALSO
.BR io_uring_get_sqe (3), io_uring_unregister_files (3)
