Release 0.6.0

- [x] release notes
- [x] integration tests pass
- [x] publish preview builds to MyGet
- [x] test source indexing after install
- [x] confirm `core.autocrlf` change doesn't break the world
- [x] add document about instructions/prerequisites for shipping releases
- [x] add documentation for enabling symbol source support in VS 
- [x] :shipit: