doc: fix broken link to DAPlink reel board fw

The repository to the DAPlink firmware for the reel board has been moved
to the Github organization PHYTEC-Messtechnik-GmbH. This commit replaces
the link in the Zephyr reel board documentation accordingly.

Signed-off-by: Jonas Remmert <j.remmert@phytec.de>
diff --git a/boards/arm/reel_board/doc/index.rst b/boards/arm/reel_board/doc/index.rst
index b3161e0..1b5043a 100644
--- a/boards/arm/reel_board/doc/index.rst
+++ b/boards/arm/reel_board/doc/index.rst
@@ -569,4 +569,4 @@
    https://www.phytec.de/reelboard/
 
 .. _DAPLink reel board Firmware:
-   https://github.com/jfischer-phytec-iot/DAPLink/tree/reel-board
+   https://github.com/PHYTEC-Messtechnik-GmbH/DAPLink/tree/reel-board