Continued to work on the documentation. Mostly API. #699

docs/api.md

docs/gui/archive.md

docs/gui/explore.md

docs/metainfo.md

docs/web.md

examples/api/authenticated.py

examples/api/getting_started.py

examples/api_use.py

examples/archive/archive_query.py

examples/tutorials/api_with_requests.py

examples/uploading/external_project_upload/example.zip

examples/uploading/external_project_upload/upload.py

mkdocs.yml

nomad/app/v1/main.py

nomad/app/v1/models.py

nomad/app/v1/routers/entries.py

nomad/mkdocs.py

requirements.txt