doc: improve documentation of the project

README.md

@@ -9,7 +9,8 @@
 <div align="center">
   <!-- last commit-->
   <a href="https://github.com/akadir/case-study/commits" title="Last Commit">
-   <img src="https://img.shields.io/github/last-commit/akadir/case-study?style=flat">
+   <img src="https://img.shields.io/github/last-commit/akadir/case-study?style=flat"
+      alt="Last commit">
   </a>
 
   <!-- Code Quality -->
@@ -40,6 +41,18 @@
   <a href="https://github.com/akadir/case-study/actions">
    <img src="https://github.com/akadir/case-study/workflows/push%20docker%20image/badge.svg"
      alt="Code Quality Check" />
+  </a>  
+
+  <!-- Docker image size -->
+  <a href="https://hub.docker.com/r/akarakoc/case-study/tags">
+   <img src="https://img.shields.io/docker/image-size/akarakoc/case-study"
+     alt="Code Quality Check" />
+  </a>  
+
+  <!-- Docker image version -->
+  <a href="https://hub.docker.com/r/akarakoc/case-study/tags">
+   <img src="https://img.shields.io/docker/v/akarakoc/case-study?label=image%20version"
+     alt="Code Quality Check" />
   </a>
 
   <!-- Quality Gate Status -->
@@ -67,8 +80,65 @@
   </a>
 </div>
 
-## Built with the Help of
+# Content
+
+   * [Run](#run)
+      * [Using Maven](#using-maven)
+      * [Using Docker](#using-docker)
+   * [UML class diagram](#uml-class-diagram)
+   * [Applied Design Patterns](#applied-design-patterns)
+   * [Pipeline Definitions](#pipeline-definitions)
+   * [Used Tools, Frameworks, Libraries etc.](#developed-with-the-help-of)
+
+## Run
+
+### Using Maven
+
+Make sure you have maven installed on your system.
+
+```sh
+git clone https://github.com/akadir/case-study.git
+cd case-study
+mvn package -DskipTests
+java -jar target/case-study.jar
+```
+
+### Using Docker
+
+Pull the latest image from [docker-hub](https://hub.docker.com/) and then run it.
+
+```
+docker pull akarakoc/case-study:1.0
+docker run akarakoc/case-study:1.0
+```
+
+## UML class diagram
+
+[![uml-diagram](.documents/uml-diagram.png)](.documents/uml-diagram.png)
+
+## Applied Design Patterns
+
+- [Chain of Responsibility](https://refactoring.guru/design-patterns/chain-of-responsibility): To validate products added into cart.
+This pattern, makes it easy to extend and re-configure validation phase. [CartEventValidator](./src/main/java/io/github/akadir/casestudy/shopping/validator/CartEventValidator.java)
+- [Strategy Pattern](https://refactoring.guru/design-patterns/strategy): Delivery cost calculation algorithms can changed in time frequently.
+Using this pattern makes it easy to adapt this algorithm changes. [DeliveryStrategy](./src/main/java/io/github/akadir/casestudy/delivery/strategy/DeliveryStrategy.java)
+- [Null Object Pattern](https://en.wikipedia.org/wiki/Null_object_pattern): In the initial phase of the [ShoppingCart](./src/main/java/io/github/akadir/casestudy/shopping/model/ShoppingCart.java#L18) DeliveryStrategy is not set yet. 
+This may lead to a NullPointerException. To prevent this from occurring, [None](./src/main/java/io/github/akadir/casestudy/delivery/strategy/None.java) DeliveryStrategy is implemented.
+
+## Pipeline Definitions
+
+All action logs can be seen from [this link](https://github.com/akadir/case-study/actions)
+and action definitions are in [this folder](./.github)
+
+- Every push that contains change in specific folders and/or files triggers two actions, build, and code quality.
+    - Build Action builds source code on 3 different Operating Systems[Ubuntu, MacOS, Windows] using 3 different java versions[8, 11, 14].
+
+- Every tagged push event triggers the [docker](https://github.com/akadir/case-study/actions?query=workflow%3A%22push+docker+image%22) 
+workflow and this workflow builds artifacts then push the docker image to the [docker hub](https://hub.docker.com/r/akarakoc/case-study/tags) 
+
+## Developed with the Help of
 
+ *  [IntelliJ IDEA](https://www.jetbrains.com/idea/) - Development environment
  *  [maven](https://maven.apache.org/) - Build automation and dependency management tool.
  *  [logback](http://logback.qos.ch/) - Logging library that implements SLF4J API
  *  [mockito](https://site.mockito.org/) - Testing framework to mock objects.