io_uring_enter man page doesn't document IORING_OP_SENDMSG_ZC

[bmerry]

There is documentation for io_uring_prep_sendmsg_zc, but the specification of the opcode is missing from io_uring_enter.2.

[davidzeng0]

also IORING_OP_FSETXATTR, IORING_OP_SETXATTR, IORING_OP_FGETXATTR, IORING_OP_GETXATTR,

[axboe]

Kind of secondary as the primary documentation should be for liburing. I will add them eventually if I have nothing else to do - or also happy to take patches to add the missing bits. It would be nice if it was complete in io_uring_enter.2.