Changelog entry for updated tool versions

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/ChangeLog.d/tool-versions.txt b/ChangeLog.d/tool-versions.txt
new file mode 100644
index 0000000..b89b384
--- /dev/null
+++ b/ChangeLog.d/tool-versions.txt
@@ -0,0 +1,4 @@
+Requirement changes
+   * Refresh the minimum supported versions of tools to build the
+     library. CMake versions older than 3.10.2 and Python older
+     than 3.6 are no longer supported.