Update Readme.md
Update Readme.md

- change `core` to `device`
- CAPS —> `DFU` and `Core`
- use `deviceName` instead of `device_id`
- standardise use of “```” for code formatting

spark/particle-cli,kennethlimcp/particle-cli,spark/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,spark/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,kennethlimcp/particle-cli,spark/particle-cli,kennethlimcp/particle-cli,kennethlimcp/particle-cli