Updated documentation to the new structure

Makefile

docs/builddocs.jl

docs/src/adapting.md

docs/src/architecture.md

docs/src/assets/architecture.png

docs/src/assets/architecture.svg

docs/src/assets/model_object.png

docs/src/assets/model_object.svg

docs/src/assets/model_structure.pdf

docs/src/assets/model_structure.png

docs/src/assets/model_structure.svg

docs/src/config.md

docs/src/developing.md

docs/src/index.md

docs/src/simulation.md

docs/src/species-dsl.md

docs/src/using.md

src/nature/macros.jl