Add Transmission and Distribution grid subcategory to electricity grid

[f-innatech]

Description of the issue

only electricity grid exists in OEO atm. I propose two subcategory additions: Transmission and Distribution grid since the differentiation is relevant.

Ideas of solution

A transmission grid is an electricity grid that transports electrical energy over long distances from large generation plants to regional or local distribution networks, operating at high rated voltage or extra high rated voltage.

Axioms: has some rated voltage high rated voltage or extra high rated voltage.

A distribution grid is an electricity grid that delivers electrical energy from the transmission grid or distributed generation sources to end users, operating at medium rated voltage or low rated voltage.

Axioms: has some rated voltage medium rated voltage or low rated voltage.

Workflow checklist

• [x] I discussed the issue with someone else than me before working on a solution
• [x] I already read the latest version of the workflow for this repository
• [x] The goal of this ontology is clear to me

I am aware that

• [x] every entry in the ontology should have a definition
• [x] classes should arise from concepts rather than from words