Added reporting & updating documentation.

documentation/en/PMD.md

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+# PMD
+
+## Rules for PMD
+
+In this project, we use PMD to ensure code quality and prevent common 
+mistakes. The rules for code analysis are defined in the pmd-ruleset.xml 
+file located in the main directory of the project.
+
+This file contains specific rule sets tailored to the project requirements. 
+Each rule set within the pmd-ruleset.xml specifies what issues PMD should 
+look for and report in the code. The configuration includes various 
+categories such as error prevention, code style, optimization, and many 
+others.
+
+A typical entry in this file looks like this:
+
+```xml
+<rule ref="category/java/bestpractices.xml/UnusedImports">
+    <priority>5</priority>
+</rule>
+```
+
+In this example, the UnusedImports rule from the best practices category is 
+used to identify unused imports in the code. The priority of this rule is set
+to 5, which indicates a low priority.
+
+To address specific needs, we can also add custom rules or modify existing
+ones. This allows us a flexible adjustment of the code analysis, which helps
+to keep our code clean, efficient, and error-free.
+
+For effective use of PMD, it is important that all team members understand
+how the pmd-ruleset.xml is structured and how it contributes to improving
+code quality. Therefore, every developer should be familiar with this
+configuration file and know how to make changes to it.
+
+## Stop build process on rule violations
+
+In the Maven project, we can control whether the build process should be
+aborted upon violations of specified rules by setting specific goals (Goals)
+of the Maven PMD or Checkstyle plugins. This function is particularly useful
+for ensuring code quality and detecting errors early in the development
+process.
+
+Depending on the project configuration, these goals can be selected for PMD:
+
+- **pmd**: Violations do not cause the build process to be aborted
+- **check**: Stricter verification and the build process is aborted upon
+violations.
+
+To enable configuration directly in the properties, the pmd.target property is used:
+
+```xml
+<pmd.target>pmd</pmd.target>
+```
+
+
+## Result of Analysis
+
+The result can be found inside target/pmd.xml.
+
+Formatting the file will make it much easier to read.