Deprecating old radio APIs and fixing docs (#289)

docs/reference/radio/packet.md

@@ -0,0 +1,19 @@
+# Packet
+
+A packet that was received by the radio.
+
+## Properties
+
+* `receivedNumber` - The number that was sent in this packet or `0` if this packet did not contain a number. See [send number](/reference/radio/send-number) and [send value](/reference/radio/send-value)
+* `text` - The string that was sent in this packet or the empty string if this packet did not contain a string. See [send string](/reference/radio/send-string) and [send value](/reference/radio/send-value)
+* `time` - The system time of the micro:bit that sent this packet at the time the packet was sent.
+* `serial` - The serial number of the micro:bit that sent this packet or `0` if the micro:bit did not include its serial number.
+* `signal` - How strong the radio signal is from `255` (weak) to `0` (strong).
+
+### See also
+
+[on data packet received](/reference/radio/on-data-packet-received),
+
+```package
+radio
+```