Update UC according to a new Functional Tree

Description

Maintenance update

• The README is updated with the link to the (rolling) Functional Tree and contains the UC mind map now.
• UC naming/numbering scheme is updated in README and in the selected UCs In future, when adding new UC or changing the existing ones, please also update the mind map when appropriate.

Related Issue

Closes #51 (closed)

Types of changes

• New Use Case
• Change request implementation