changelog: Addressed review comments #6

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/ChangeLog.d/twos_complement_representation.txt b/ChangeLog.d/twos_complement_representation.txt
new file mode 100644
index 0000000..fa49859
--- /dev/null
+++ b/ChangeLog.d/twos_complement_representation.txt
@@ -0,0 +1,3 @@
+Requirement changes
+   * Sign-magnitude and one's complement representations for signed integers are
+     not supported. Two's complement is the only supported representation.