doc/releases: v2.6.0: Update for shields impacts

Update v2.6.0 release note with shields addition.

Signed-off-by: Erwan Gouriou <[email protected]>

Author: erwango

doc/releases/release-notes-2.6.rst

@@ -296,6 +296,11 @@ Boards & SoC Support
 
 * Added support for these following shields:
 
+  * FTDI VM800C Embedded Video Engine Board
+  * Generic ST7735R Display Shield
+  * NXP FRDM-STBC-AGM01
+  * Semtech SX1272MB2DAS LoRa Shield
+
 Drivers and Sensors
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