Make oral exam transcript template download more obvious

Steps:

1. Attempt to submit an oral exam transcript.
2. Fail to find the template.

I’ve had two peers ask me in the last week about where I got the template from :/

This is related to https://gitlab.ethz.ch/vseth/0403-isg/libraries/npm-vseth-theme/-/issues/5. As that doesn’t look like it will see progress any time soon, I’d suggest to just put the template behind an explicit button: