Fix incorrect case in changelog entry

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/ChangeLog.d/fix-printf-specifiers.txt b/ChangeLog.d/fix-printf-specifiers.txt
index 72d08c0..4fc575a 100644
--- a/ChangeLog.d/fix-printf-specifiers.txt
+++ b/ChangeLog.d/fix-printf-specifiers.txt
@@ -2,7 +2,7 @@
    * Add printf function attributes to mbedtls_debug_print_msg because we were
      not actually getting any printf format specifier warnings prior to this.
      Also add extra printf compiler warning flags to builds.
-Requirement Changes
+Requirement changes
    * Use %zu for print of type size_t in new work, however please do not use
      them in backports, and preferably not in code that needs to be
      backported.