docs(changelog): add 'dice' scope

To cover the DICE related works such as
DICE Protection Environment (DPE) integration
with the measurd boot framework.

Signed-off-by: Tamas Ban <tamas.ban@arm.com>
Change-Id: I9769b7bddbd1d269705ebff1d15870ab928fd8ef

changelog.yaml

@@ -804,6 +804,9 @@ subsections:
         deprecated:
           - lib/psa
 
+      - title: DICE Protection Environment
+        scope: dice
+
       - title: Context Management
         scope: context-mgmt