Added stuff to docs, try to make it work correctly

.gitlab-ci.yml

README.rst

docs/api/empyre.fields.rst

docs/api/empyre.io.rst

docs/api/empyre.models.rst

docs/api/empyre.reconstruct.rst

docs/api/empyre.rst

docs/api/empyre.vis.rst

docs/api/modules.rst

docs/fields.rst

src/empyre/fields/field.py