Adds GitHub account of D. Espen

Signed-off-by: Frank Schnicke <frank.schnicke@iese.fraunhofer.de>

Author: FrankSchnicke

README.md

@@ -43,7 +43,7 @@ We always look for contributions, bug reports, feature requests etc. Simply open
 |:--| -- | -- |
 | Sebastian Bader | Fraunhoder IAIS | [sebbader](https://github.com/sebbader) |
 | Matthias Böckmann | Fraunhoder IAIS | [maboeckmann](https://github.com/maboeckmann) |
-| Daniel Espen | Fraunhoder IESE | []() |
+| Daniel Espen | Fraunhoder IESE | [daespen](https://github.com/daespen) |
 | Michael Jacoby | Fraunhoder IOSB (ILT) | [mjacoby](https://github.com/mjacoby) |
 | Jens Müller | Fraunhoder IOSB | []() |
 | Chang Qin | Fraunhoder IAIS | [changqin26](https://github.com/changqin26) |