Add documentation for RELATIONS list clarifying ontology design principles

[chigwell]

User Story
As a new contributor to the eknowledge project,
I want comprehensive documentation for the RELATIONS list in relations.py
so that I can understand the ontology design principles when adding or modifying relationships.

Background
The RELATIONS list in relations.py contains 50+ relationship types (e.g., has_property, derived_from, temporally_related_to) but lacks design context. Contributors extending this ontology may:

• Misinterpret relationship scopes (e.g., confusing part_of vs belongs_to)
• Introduce redundant relationships
• Overlook hierarchical patterns (e.g., is_a vs subclass_of)

Current risks include inconsistent relationship additions and increased maintenance costs. The absence of design rationale forces contributors to reverse-engineer patterns from existing entries.

Acceptance Criteria

• Modify relations.py to add a docstring directly above the RELATIONS list declaration
• Docstring must include:
  • Purpose of the ontology (e.g., balancing general knowledge graphs vs domain-specific needs)
  • Hierarchy/nesting principles (e.g., why has_attribute and has_property are distinct)
  • Criteria for adding new relationships (e.g., "Avoid duplicating semantic scope of existing terms")
  • Examples of edge cases and how they were resolved (e.g., located_in vs contains)
• Validate via:
  1. Docstring appears in code completion tools (VS Code/PyCharm)
  2. All examples in the docstring match actual RELATIONS entries
  3. pytest runs pass without modifications to test logic
  4. No markdown formatting – use standard Python docstring syntax