docs(learning material): add learning material urls
docs(learning material): add learning material urls

marc-inn/ng2-play,btford/ng2-play,marc-inn/ng2-play,rolandjitsu/ng2-lab,rolandjitsu/ng2-play,rolandjitsu/ng2-lab,rolandjitsu/angular-lab,rolandjitsu/ng2-play,rolandjitsu/angular-lab,btford/ng2-play,btford/ng2-play,marc-inn/ng2-play,marc-inn/ng2-play,rolandjitsu/angular-lab,btford/ng2-play,rolandjitsu/angular-lab,rolandjitsu/ng2-play,rolandjitsu/ng2-lab,rolandjitsu/ng2-play,rolandjitsu/ng2-lab