Update README.md

Adding info about [dlogg](https://github.com/NCrashed/dlogg) library. It was designed for commercial use in daemons and concurrent applications.

Features:
* Customization of messages at compile-time
* Lazy logging
* Buffered logger
* Log rotating support 

The library was developed before std.logger proposal and used by Dash and my JSON RPC server [pgator](https://github.com/DSoftOut/pgator).