Updated README

## Roadmap

### Client

- [x] Parse rsync://

- [x] Connect to rsync server

- [x] Hand shake

- [x] Send argument list

- [x] Fetch the file list

- [x] Request & download files

- [x] File List Caching

- [ ] CLI

#### Rsync wire protocol 27:

- [x] Parses rsync://

- [x] Connects to rsync server

- [x] Hand shaking

- [x] Sends argument list

- [x] Fetches the file list

- [x] Requests & download files

- [ ] Handles error

#### File List Caching

- [x] BoltDB backend

- [ ] Redis backend

- [x] Diff 

- [x] Update

#### Storage backend

- [x] Minio: supports regular files

- [ ] Minio: supports folder & symlink

#### Other

- [x] CLI

## Detailed Information

#### What's the difference between rsync and rsync-os