docs: Update website documentation

Change-Id: I01fa76eabc327a5638627b27bc51e6330d5ad210
Refs: #4213, #4039
diff --git a/docs/source/metric.rst b/docs/source/metric.rst
index 29b2973..67aa355 100644
--- a/docs/source/metric.rst
+++ b/docs/source/metric.rst
@@ -248,7 +248,7 @@
 Content store trace helper
 --------------------------
 
-NOTE: This tracer works ONLY when the content store structure of ndnSIM is used!
+NOTE: This tracer works ONLY when the OldContentStore structure is used!
 
 - :ndnsim:`ndn::CsTracer`