Insert new hw video links (#1910)

docs/reference/radio/on-received-number.md

@@ -11,6 +11,14 @@ radio.onReceivedNumber(function (receivedNumber) {})
 
 * **receivedNumber**: The [number](/types/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)
 
+## ~ hint
+
+Watch this video to see how the radio hardware works on the @boardname@:
+
+https://www.youtube.com/watch?v=Re3H2ISfQE8
+
+## ~
+
 ## Examples
 
 ### Tell me how fast

docs/reference/radio/on-received-string.md

@@ -10,6 +10,14 @@ radio.onReceivedString(function (receivedString) {})
 
 * **receivedString**: The [string](/types/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)
 
+## ~ hint
+
+Watch this video to see how the radio hardware works on the @boardname@:
+
+https://www.youtube.com/watch?v=Re3H2ISfQE8
+
+## ~
+
 ## Example
 
 This program continuously sends a cheerful message. It also receives a messages from nearby @boardname@s. It shows these messages on the screen.

docs/reference/radio/on-received-value.md

@@ -11,6 +11,14 @@ radio.onReceivedValue(function (name, value) {})
 * **name**: a [string](/types/string) that is a name for the value received.
 * **value**: a [number](/types/number) that is the value received.
 
+## ~ hint
+
+Watch this video to see how the radio hardware works on the @boardname@:
+
+https://www.youtube.com/watch?v=Re3H2ISfQE8
+
+## ~
+
 ## Example
 
 This program keeps sending numbers that say how fast the @boardname@ is

docs/reference/radio/send-number.md

@@ -10,6 +10,13 @@ radio.sendNumber(0);
 
 * **value**: a [number](/types/number) to send.
 
+## ~ hint
+
+Watch this video to see how the radio hardware works on the @boardname@:
+
+https://www.youtube.com/watch?v=Re3H2ISfQE8
+
+## ~
 
 ## Examples
 

docs/reference/radio/send-string.md

@@ -11,6 +11,13 @@ radio.sendString("Hello!")
 
 * **msg**: a [string](/types/string) to send by radio.
 
+## ~ hint
+
+Watch this video to see how the radio hardware works on the @boardname@:
+
+https://www.youtube.com/watch?v=Re3H2ISfQE8
+
+## ~
 
 ## Example: Two-way radio
 

docs/reference/radio/send-value.md

@@ -12,6 +12,14 @@ radio.sendValue("name", 0);
 * **name**: a [string](/types/string) that is the name of the value to send.
 * **value**: a [number](/types/number) that is the value to send.
 
+## ~ hint
+
+Watch this video to see how the radio hardware works on the @boardname@:
+
+https://www.youtube.com/watch?v=Re3H2ISfQE8
+
+## ~
+
 ## Example: Broadcasting acceleration
 
 This program sends your @boardname@'s **acceleration** (amount it is