sched: add kernel-doc for struct clone_args

#define CLONE_IO		0x80000000	/* Clone io context */

#ifndef __ASSEMBLY__

/*

 * Arguments for the clone3 syscall

/**

 * struct clone_args - arguments for the clone3 syscall

 * @flags:       Flags for the new process as listed above.

 *               All flags are valid except for CSIGNAL and

 *               CLONE_DETACHED.

 * @pidfd:       If CLONE_PIDFD is set, a pidfd will be

 *               returned in this argument.

 * @child_tid:   If CLONE_CHILD_SETTID is set, the TID of the

 *               child process will be returned in the child's

 *               memory.

 * @parent_tid:  If CLONE_PARENT_SETTID is set, the TID of

 *               the child process will be returned in the

 *               parent's memory.

 * @exit_signal: The exit_signal the parent process will be

 *               sent when the child exits.

 * @stack:       Specify the location of the stack for the

 *               child process.

 * @stack_size:  The size of the stack for the child process.

 * @tls:         If CLONE_SETTLS is set, the tls descriptor

 *               is set to tls.

 *

 * The structure is versioned by size and thus extensible.

 * New struct members must go at the end of the struct and

 * must be properly 64bit aligned.

 */

struct clone_args {

	__aligned_u64 flags;