fixes

[ghost]

Updated README.md with updates + todo:

What this fork does:

• Integrate 2 issues reported by other users: this and that.
• Slight change in the way detected devices are computed. The newer BLE lib breaks compatibility with the way the original sketch worked, see this. Slight change in the MyAdvertisedDeviceCallbacks class and in ScanBLE.
• Turn on the ESP32 onboard LED for a bit after MQTT update.

Still to do:

• Look at BodyMetrics is outdated #1