Some details on Design Patterns section.

README.md

@@ -1109,22 +1109,28 @@ You'll get more graph practice in Skiena's book (see Books section below) and th
 
 - [ ] **Design patterns**
     - [x] Quick UML review: https://www.youtube.com/watch?v=3cmzqZzwNDM&list=PLGLfVvz_LVvQ5G-LdJ8RLqe-ndo7QITYc&index=3
-    - [ ] Learn these patterns:
-        - [ ] strategy
+    - [x] Learn these patterns:
+        - [x] strategy
         - [x] singleton
         - [x] adapter
-        - [ ] prototype
-        - [ ] decorator
-        - [ ] visitor
-        - [x] factory
-        - [ ] facade
-        - [ ] observer
-        - [ ] proxy
-        - [ ] delegate
+        - [x] prototype
+        - [x] decorator
+        - [x] visitor
+        - [x] factory, abstract factory
+        - [x] facade
+        - [x] observer
+        - [x] proxy
+        - [x] delegate
+        - [x] command
+        - [x] state
+        - [x] memento
+        - [x] iterator
+        - [x] composite
+        - [x] flyweight
     - [x] Chapter 6 (Part 1) - Patterns: https://youtu.be/LAP2A80Ajrg?list=PLJ9pm_Rc9HesnkwKlal_buSIHA-jTZMpO&t=3344
     - [x] Chapter 6 (Part 2) - Abstraction-Occurrence, General Hierarchy, Player-Role, Singleton, Observer, Delegation: https://www.youtube.com/watch?v=U8-PGsjvZc4&index=12&list=PLJ9pm_Rc9HesnkwKlal_buSIHA-jTZMpO
     - [x] Chapter 6 (Part 3) - Adapter, Facade, Immutable, Read-Only Interface, Proxy: https://www.youtube.com/watch?v=7sduBHuex4c&index=13&list=PLJ9pm_Rc9HesnkwKlal_buSIHA-jTZMpO
-    - [ ] Series of short videos (27 videos): https://www.youtube.com/playlist?list=PLF206E906175C7E07
+    - [x] Series of videos (27 videos): https://www.youtube.com/playlist?list=PLF206E906175C7E07
     - [ ] Head First Design Patterns: https://www.amazon.com/Head-First-Design-Patterns-Freeman/dp/0596007124
         - I know the canonical book is "Design Patterns: Elements of Reusable Object-Oriented Software", but Head First is great for beginners to OO.
     - [ ] Handy reference: 101 Design Patterns & Tips for Developers: https://sourcemaking.com/design-patterns-and-tips