doc: release notes: Shields updates for v2.7.0

Update V2.7.0 release notes document with noticeable changes
related to shields.

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

Author: erwango

doc/releases/release-notes-2.7.rst

@@ -243,6 +243,8 @@ Boards & SoC Support
 
 * Added support for these following shields:
 
+  * 4.2inch epaper display (GDEW042T2)
+  * X-NUCLEO-EEPRMA2 EEPROM memory expansion board
 
 Drivers and Sensors
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