NEW: sync the code of DJI Payload-SDK version 2.2.1 released on January 20 2021.

Signed-off-by: DJI-Martin <DJI-Martin@dji.com>

sample/platform/linux/manifold2/README.txt

@@ -0,0 +1,38 @@
+Payload SDK Linux Sample.
+
+Test Environment:
+Hardware:               Manifold2-C/G
+Serial:                 USB-to-Serial Controller CP210x
+C Compiler:             GCC version 5.4.0 20160609
+CMake Version:          Cmake version 3.5.1
+IDE:                    CLion 2020.3.1
+
+Communication Serial Configuration:
+Baud Rate:              460800
+
+Network Port Configuration:
+IP Address:             Auto Config (Need root permission)
+Network Port:           Auto Config
+NetMask:                Auto Config
+Gateway:                Auto Config
+
+====== The steps to run the Payload SDK linux sample  ======
+Step 1 : modify related device information, such as device name of network or uart, uart baud rate.
+
+Step 2 : fill in your app info to file with path 'sample/platform/linux/manifold2/application/app_info.h'.
+This info can be obtained by logging in to the developer website https://developer.dji.com/payload-sdk.
+
+Step 3 : build source file, use following cmd:
+cd source_code_dir/project
+mkdir build
+cd build
+cmake ..
+make
+
+Step 4 : Manifold should connect to Skyport 2.0/XPort via usb-to-serial controller and network cable, make sure the
+serial pins are connected properly.
+
+Step 5 : use the root permission to execute this program, use following cmd:
+sudo ./psdk_demo
+
+Step 6: open DJI Pilot APP/MSDK APP to use the payload demo functions.