Improve workshop documentation

[teodoran]

The documentation could probably need a brush-up. A couple of issues was noted when running the workshop for the first time:

• Some participants was confused about when to use the online challenge instance of the Sticky Notes to hunt for flags. Instead they ended up looking for fags in their local instance of Sticky Notes. This could probably be improved if the introduction was a bit more thorough.
• The introduction to each vulnerability is a bit short. It should be improved to give participants a better understanding of the vulnerability in general, before they start performing an exploit in the fault section.
• It would be beneficial if someone other than the original author goes through the workshop, and updates the documentation where it's confusing, or otherwise lacking.

[teodoran]

The workshop introduction now does a better job of describing how participants should juggle between the local and online instance of Sticky Notes. The other parts of the documentation might still be improved though.