Added some module level descriptors and had a go at the token guide.

packages/python/README.md

packages/python/docs/index.md

packages/python/docs/snippets/combining.ipynb

packages/python/docs/snippets/text.ipynb

packages/python/docs/tokens.md

packages/python/src/snip/api/__init__.py

packages/python/src/snip/api/exceptions.py

packages/python/src/snip/api/request.py

packages/python/src/snip/api/schemas.py

packages/python/src/snip/api/snippets.py

packages/python/src/snip/snippets/__main__.py

packages/python/src/snip/token/storage/file_store.py