task: Explanations and grammar fixes for all the GoF patterns (#1791)

* Grammatical fixes to command pattern

* Update bridge pattern readme

* Fixes to builder pattern grammar

* Update chain of responsibility

* Improvements to the composite example

* Fixes to headings

* Minor updates to decorator pattern

* Update facade

* Update factory example

* Update factory method

* Update flyweight

* Interpreter explanation

* Update iterator readme

* Add explanation for mediator pattern

* Grammatical fixes to memento

* Grammar fixes for observer

* Update explanation for the prototype pattern

* Proxy pattern grammar fixes

* Update singleton

* Grammar fixes to state pattern

* Grammar fixes for strategy

* Grammar fixes, template method

* Grammar fixes for visitor

* Fix typo

command/src/main/java/com/iluwatar/command/App.java

@@ -26,7 +26,7 @@ package com.iluwatar.command;
 /**
  * The Command pattern is a behavioral design pattern in which an object is used to encapsulate all
  * information needed to perform an action or trigger an event at a later time. This information
- * includes the method name, the object that owns the method and values for the method parameters.
+ * includes the method name, the object that owns the method, and values for the method parameters.
  *
  * <p>Four terms always associated with the command pattern are command, receiver, invoker and
  * client. A command object (spell) knows about the receiver (target) and invokes a method of the