docs: add diagrams for identity map, intercepting filter, interpreter, iterator

identity-map/README.md

@@ -31,6 +31,10 @@ Wikipedia says
 
 > In the design of DBMS, the identity map pattern is a database access design pattern used to improve performance by providing a context-specific, in-memory cache to prevent duplicate retrieval of the same object data from the database.
 
+Sequence diagram
+
+![Identity Map sequence diagram](./etc/identity-map-sequence-diagram.png)
+
 ## Programmatic Example of Identity Map Pattern in Java
 
 For the purpose of this demonstration in Java programming, assume we have already created a database instance, showcasing the Identity Map pattern to avoid duplicate objects in memory.