Flask-opensearch

- Fixes issue that prevented code from being published to pypi in earlier versions. Changes `py_modules` kwarg in `setup.py` to `packages`
- Optimizes Dockerfile caching

- Improved quickstart documentation in the readme.

Initial Release

What's Changed
* Read readme into setup.py by galbwe in https://github.com/galbwe/Flask-Opensearch/pull/2
* Set long description content type to markdown by galbwe in https://github.com/galbwe/Flask-Opensearch/pull/3


**Full Changelog**: https://github.com/galbwe/Flask-Opensearch/compare/v1.0.0...v1.0.0b