Adds credits (#25)

Signed-off-by: Daniel Kastl <daniel@georepublic.de>

Author: dkastl

README.md

@@ -91,6 +91,10 @@ with release notes.
 - [Nisai Nob](https://github.com/nobnisai)
 - ... [and others](https://github.com/gtt-project/redmine_gtt_smash/graphs/contributors)
 
+## Credits
+
+This plugin development was funded by [Hyakumori](https://www.hyakumori.com/). 
+
 ## LICENSE
 
 This program is free software. See [LICENSE](LICENSE) for more information.