doc: fix path to DECT shell sample

The path to the sample was missing the dect_phy folder.
Added now.

Signed-off-by: Pekka Niskanen <[email protected]>

Author: peknis

samples/dect/dect_phy/dect_shell/README.rst

@@ -1047,7 +1047,7 @@ Example: starting of cluster beacon and sending RA data to it
 Building
 ********
 
-.. |sample path| replace:: :file:`samples/dect/dect_shell`
+.. |sample path| replace:: :file:`samples/dect/dect_phy/dect_shell`
 
 .. include:: /includes/build_and_run_ns.txt