Document that SDO Block Upload is not implemented

[follower]

While a function named canopen_sdo_upload_block() exists, it has no implementation:

libcanopen/canopen/canopen-com.c

Lines 470 to 475 in 6e4758b

	int
	canopen_sdo_upload_block(int sock, uint8_t node, uint16_t index, uint8_t subindex,
	uint8_t *data, uint32_t data_len)
	{
	return -1;
	}

A Python wrapper function does exist but uses the unimplemented C function:

libcanopen/python/pycanopen/CANopen.py

Lines 222 to 232 in 6e4758b

	def SDOUploadBlock(self, node, index, subindex, size):
	"""
	Block SDO upload.
	"""
	data = create_string_buffer(int(size))
	ret = libcanopen.canopen_sdo_upload_block(self.sock, c_uint8(node), c_uint16(index), c_uint8(subindex), data, c_uint16(size));
	if ret != 0:
	raise Exception("CANopen Block SDO upload error")
	return binascii.hexlify(data)

The Python wrapper function used to mention that the function was unimplemented but the note was removed here.

[follower]

Also here:

libcanopen/bin/rs-canopen-pdo-upload.c

Lines 75 to 76 in 6e4758b

	// XXX: incomplete
	//canopen_frame_set_sdo_upload(&canopen_frame, node, index, subindex);