Add freiheit.com to list of sponsors

Author: flodiebold

README.md

@@ -11,6 +11,7 @@ Work on the Rust Analyzer is sponsored by
 
 [<img src="https://user-images.githubusercontent.com/1711539/58105231-cf306900-7bee-11e9-83d8-9f1102e59d29.png" alt="Ferrous Systems" width="300">](https://ferrous-systems.com/)
 - [Mozilla](https://www.mozilla.org/en-US/)
+- [freiheit.com](https://www.freiheit.com)
 
 ## Language Server Quick Start