DFU成功后烧录的hex不能从app启动，烧录了SD bootloader app后在dfu广播

这是应为NORDIC DFU还差一个bootloader_seting.hex
使用如下指令生成：
nrfutil settings generate --family NRF52 --application yourApplication.hex --application-version 0 --bootloader-version 0 --bl-settings-version 1 bootloader_setting.hex
NRF52 DFU的完整步骤是：
Step A. Generate keys

Step B. Build the bootloader

Step C. Generate DFU .zip packet

Step D. Test DFU

Step E. Update new application firmware (Optional)

Appendix - Advanced features

1. Combine application, bootloader, bootloader setting and softdevice image 这一步就是生成bootloader setting，具体见
   链接：https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/getting-started-with-nordics-secure-dfu-bootloader#h61sjziauupw1j397q9s9ldr01q4j6d5 命令： nrfutil settings generate --family NRF52 --application yourApplication.hex --application-version 0 --bootloader-version 0 --bl-settings-version 1 bootloader_setting.hex

2. Buttonless DFU

3. Update softdevice and bootloader

4. Bond forwarding with buttonless DFU

5. DFU Master code

6. Background DFU