Merge remote-tracking branch 'origin/master'

# Conflicts:
#	README.md

Author: kuba

README.md

@@ -17,28 +17,30 @@ This project is set of simple examples of usage of different design patterns in
 - [bridge](https://medium.com/better-programming/what-is-bridge-design-pattern-89bfa581fbd3)
 - [chain of responsibility](https://medium.com/@j.kapuscik2/what-is-chain-of-responsibility-design-pattern-ff4d22abd124)
 - [visitor](https://medium.com/@j.kapuscik2/what-is-visitor-design-pattern-8451fb75876)
+- [command](https://medium.com/@j.kapuscik2/what-is-cqrs-command-design-pattern-5d400fd9f93a)
 - [null object](https://medium.com/@j.kapuscik2/what-is-null-object-design-pattern-f3b4d3d28636)
 
-Following patterns have so far been described:
+### Following patterns have so far been described:
 
-Creational:
+#### Creational:
 1. [Factory Method](/creational/factory_method)
 2. [Abstract Factory](/creational/abstract_factory)
 3. [Singleton](/creational/singleton)
 4. [Builder](/creational/builder)
 5. [Prototype](/creational/prototype)
 
-Behavioral:
+#### Behavioral:
 1. [Iterator](/behavioral/iterator)
 2. [Observer](/behavioral/observer)
 3. [State](/behavioral/state)
 4. [Strategy](/behavioral/strategy)
 5. [Template Method](/behavioral/template_method)
 6. [Chain of Responsibility](/behavioral/chain_of_responsibility)
 7. [Visitor](/behavioral/visitor)
-8. [Null Object](/behavioral/null_object)
- 
-Structural:
+8. [Command](/behavioral/command)
+9. [Null Object](/behavioral/null_object)
+
+#### Structural:
 1. [Adapter](/structural/adapter)
 2. [Decorator](/structural/decorator)
 3. [Proxy](/structural/proxy)