feat(neoverse-rd): add scope for RD-Fremont variants

As RD-Fremont and its variants would need a dedicated scope for use,
define the scope 'rdfremont' under the subsection within Neoverse-RD
platforms.

Change-Id: I7066824a33edd893e187ec397298b49392ac35da
Signed-off-by: Rohit Mathew <rohit.mathew@arm.com>
diff --git a/changelog.yaml b/changelog.yaml
index 6f2458e..7d8760e 100644
--- a/changelog.yaml
+++ b/changelog.yaml
@@ -241,6 +241,9 @@
               - title: RD-N2
                 scope: rdn2
 
+              - title: RD-Fremont
+                scope: rdfremont
+
                 deprecated:
                   - board/rdn2