Links to angry games and yivitube hardcoded to staging

[w-ensink]

The links to the yivitube and angry games are currently hard coded to staging, which means they're broken for anyone who doesn't have the staging scheme installed.

irma-demos/index.html

Line 43 in 966942b

<button class="custom-button" onclick="window.location.href='https://angrygames.staging.yivi.app/'">Angry Games demo</button>

and

irma-demos/index.html

Line 47 in 966942b

<button class="custom-button" onclick="window.location.href='https://yivitube.staging.yivi.app'">YiviTube</button>