Add myself to AUTHORS.rst
Add myself to AUTHORS.rst

Signed-off-by: Christoph Witzany <7abde52c298496fa169fb750f91f213a282142af@web.crofting.com>

TribeMedia/synapse,matrix-org/synapse,TribeMedia/synapse,matrix-org/synapse,TribeMedia/synapse,matrix-org/synapse,TribeMedia/synapse,matrix-org/synapse,matrix-org/synapse,TribeMedia/synapse,matrix-org/synapse