Unhiding UML2 5.5.0.
diff --git a/downloads/hidden.txt b/downloads/hidden.txt
index 69541c2..966f518 100644
--- a/downloads/hidden.txt
+++ b/downloads/hidden.txt
@@ -1,2 +1 @@
-modeling/mdt/5.5.0/R201812031331
 modeling/mdt/6.6.0/R201812101441