Add MarkdownDisplay and MarkdwonWriteFile methods

src/main/java/re/forestier/edu/Main.java

src/main/java/re/forestier/edu/rpg/MarkdownDisplay.java

src/main/resources/Markdown.md

src/test/java/re/forestier/edu/MarkdownTest.java

...va/re/forestier/edu/MarkdownTest.testDisplay.approved.txt