[Securing Communication] Leftover tasks

[carrrina]

1. Should we gitignore media/ dir generated in slides/? And/or call it _media/?
2. Proper Naming challenge: use template seed for flag; don't hardcode it.
3. Client Certificate Authentication challenge: use template seed for flag; don't hardcode it.
4. Update Client Certificate Authentication solution to use the files from the archive received by the participants, i.e., create a new client cert from it. See old attendance forms from participants for commands/writeups. :)
5. Ask RD / see what is it about with the files in the PR on the internals repo, if they were used in the session, or as demo, or as further reading, or new challenges etc.
6. Delete unnecessary files from session dir: media etc.