Documentation : Introduce distinction between "main" and "supportive" shapes

[tfrancart]

We need 2 sections in the documentation : "Main Entities" vs. "Supportive Entities"

Algorithm to determine "main" vs. "supportive" entities:

1. Explicit annotation : If at least one NodeShape is found with the annotation shacl-play:main true, then:

• All NodeShape with shacl-play:main true are "Main"
• All others are "Supportive"

2. If not predicate shacl-play:main is found, then:

• All NodeShape with a target are "Main" (sh:targetClass or sh:target or sh:targetNode or sh:targetObjectsOf or sh:targetSubjectsOf)
• All NodeShape without a target are "Supportive"

Labels:

• en : "Main Entities" / "Supportive Entities"
• fr : "Entités principales" / "Entités secondaires"