Fix null links Closes https://github.com/gjtorikian/markdowntutorial.com/issues/50
Fix null links
Closes https://github.com/gjtorikian/markdowntutorial.com/issues/50

gjtorikian/markdowntutorial.com,gjtorikian/markdowntutorial.com,gjtorikian/markdowntutorial.com,gjtorikian/markdowntutorial.com