doc: Remove micro:bit Pong game from release notes

It did not make the 1.8 release, was added by mistake.

Signed-off-by: Carles Cufi <[email protected]>

Author: carlescufi

doc/release-notes-1.8.rst

@@ -96,7 +96,6 @@ Bluetooth
 * Added HCI Controller to Host flow control support in both Host and Controller
 * BR/EDR: Added HFP (e)SCO audio channel establishment support
 * BR/EDR: Added support for a functional SDP server
-* micro:bit: Added a new sample that implements a game of Pong over BLE
 
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