Elektra: Use Case: Adding keys

Elektra 0.8.24

Use Case: Adding keys

## Summary

- Title: Adding keys
- Scope: Configuration
- Level: User Goal
- Actors: User (usually a sysadmin)
- Brief: User adds a key (to a subtree).

## Scenarios

- Precondition: View configuration of an instance.
- Main success scenario: User creates a new key (in a subtree).
- Alternative scenario: User enters data that violates a validation rule, an error message is shown.
- Error scenario: Technical problems while persisting to the key database. The user is informed about the problem.
- Postcondition: The new key is persisted to the database.
- Non-functional Constraints: -