chore(demo): change github branch to master

Author: javier-godoy

src/test/java/com/flowingcode/vaadin/addons/syntaxhighlighter/SyntaxHighlighterDemoView.java

@@ -30,7 +30,7 @@
 @ParentLayout(DemoLayout.class)
 @Route("syntax-highlighter")
 @GithubLink("https://github.com/FlowingCode/SyntaxHighlighter")
-@GithubBranch("initial-implementation")
+@GithubBranch("master")
 public class SyntaxHighlighterDemoView extends TabbedDemo {
 
   public SyntaxHighlighterDemoView() {