Add introduction page

[CJGutz]

Is your feature request related to a problem?

Verifiable credentials and eIDAS 2.0 are still hard concepts to grasp. People need an introduction to this.

Describe the solution you would like

Add to the page introduction. Formulate the important concepts so it is possible to understand for beginners.
Write about VC and eIDAS 2.0.
Points to write about eIDAS 2.0:

• Difference from todays electronic id
• Away from username and password
• A solution across borders
• Service to ecosystem; there is less reliant on choosing a specific service to authenticate.

Acceptance Criteria

Include both eIDAS 2.0 and VC information.