Add ChangeLog for moving OID string conversion functions

Signed-off-by: Harry Ramsey <harry.ramsey@arm.com>
diff --git a/ChangeLog.d/split-numeric-string-conversions-out-of-the-oid-module.txt b/ChangeLog.d/split-numeric-string-conversions-out-of-the-oid-module.txt
new file mode 100644
index 0000000..2ccd39f
--- /dev/null
+++ b/ChangeLog.d/split-numeric-string-conversions-out-of-the-oid-module.txt
@@ -0,0 +1,4 @@
+Changes
+	 * Functions regarding numeric string conversions for OIDs have been moved
+		 from the OID module and now reside in X.509 module. This helps to reduce
+		 the code size as these functions are not commonly used outside of X.509.