Change markdown header tab anchor links to buttons

What does this MR do?

Changes markdown header tab anchor links to buttons. (see https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21988#note_105636972)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides

app/assets/javascripts/projects/project_new.js

@@ -147,7 +147,7 @@ const bindEvents = () => {
 
   $projectImportUrl.keyup(() => deriveProjectPathFromUrl($projectImportUrl));
 
-  $projectName.keyup(() => {
+  $projectName.on('keyup change', () => {
     onProjectNameChange($projectName, $projectPath);
     hasUserDefinedProjectPath = $projectPath.val().trim().length > 0;
   });