docs: Align Relations in Metamodel to SysML

[hoe-jo]

The relations between requirements and architectural elements differ from the SysML standard (see e.g. https://en.wikipedia.org/wiki/Requirement_diagram). They would have to be renamed:

Requirements: satisfies -> derived_from (and satisfied_by -> derives)
Architectural Elements: fulfils -> satisfies (and fulfilled_by -> satisfied_by)

[AlexanderLanin]

@FScholPer please take a look to not reassign teams