build(changelog): add new scope for DRTM service

Added new scope for DRTM service.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: Idffb178026ef2910102b55e640d5f5bf904e6064
diff --git a/changelog.yaml b/changelog.yaml
index d2dc992..ecb401e 100644
--- a/changelog.yaml
+++ b/changelog.yaml
@@ -589,6 +589,9 @@
           - title: SPM MM
             scope: spm-mm
 
+      - title: DRTM
+        scope: drtm
+
   - title: Libraries
 
     subsections: