update README.md

README.md

 # Nrfx toolbox
+
+- DFU tool  
+Using [`py-nrfutil`](https://github.com/NordicSemiconductor/pc-nrfutil)  
+Features:  
+    1. Generating and displaying keys
+    2. and displaying bootloader settings
+    3. Generating DFU packages
+    4. Performing a DFU
+    5. Generating HEX files for zigbee
+    6. Customizing the init packet
+    7. Displaying version information
+- Programmer