[Training] Prepare general training material on onion services

The training material will give an overview of onion services and its benefits.

As more organisations adopt onion services and the interest in deploying onion services has increased, we need to have a resource at hand to use when talking to human rights defenders and organisations, journalists, etc.

Important notes:

• The slides will not be technical, the most technical component will be about OnionShare.
• We won't mention deployment tools, just explaining what it is and its benefits.
• Showcase popular onion services: Twitter, news services, etc.
• Demystifying the Tor network, why we don't call it the "dark web."

Feedback:

• For links, let's use 'https://' instead of just 'www.example.com'.
• The Tor Browser screenshots shouldn't have any third party add-on installed or visible (e.g. uBlock origin, Bitwarden, etc). It should use a vanilla Tor Browser.
• In "Tools that run on Tor" section, how did you make the tool curation? Should we include Ricochet Refresh too?
• For the Dark/Deep web section, I think we could add the iceberg image and discuss how that is silly/misinformation. Starting by the iceberg position itself, which is something very unstable: check this and this thread.
• For the hands on exercise, I'd use OnionShare file sharing feature instead, as this can be more useful for journalists (sharing files secretly) than hosting a static website. Or maybe we can include both in the presentation, so the facilitator can pick one exercise?
• The "How the Tor Project can support you with Onion Servicing" part I'd move to before the "Latest Development".