Consider removing link to workshop survey

### How could the content be improved?

We link to the post workshop survey in the curriculum. If someone follows this link, it will not match the survey responses up to a specific training. To match survey responses to a specific training, learners must use a link that includes the workshop slug. This typically comes from the training website or is provided by the administrator.

### Which part of the content does your suggestion apply to?

https://carpentries.github.io/instructor-training/25-wrap-up.html#post-workshop-surveys

Open 25-wrap-up.html and inspect the “Post-workshop surveys” section identified in the issue. Remove the generic post-workshop survey link, leaving learners directed to a training-specific link supplied by the training website or administrator. Done means the curriculum no longer links to the non-specific survey URL.

Written by the indexing model from the issue text.