[Synology] Add logging section (openhab#543)

Signed-off-by: Christian Häussler <[email protected]> (github: @cniweb)

Author: cniweb

installation/synology.md

@@ -61,3 +61,14 @@ The administrator can also create a public shared folder if desired.
 
 Synology does not document which models will automatically create a public folder.
 Refer to the Synology knowlegde base article on [Shared Folder](https://www.synology.com/en-us/knowledgebase/DSM/help/DSM/AdminCenter/file_share_desc) to learn more.
+
+## Logging
+
+The openHAB2 log files can be found here:
+`/volume1/@appstore/openHAB2/userdata/logs/`.
+
+From Version openHAB-2.2.0.006 the SPK generates two log files located at `/var/log/`.
+
+The first log file `openHAB2-install.log` will be generated during the installation. If you can't install the openHAB2 SPK, please have a look inside the file.
+
+The second log `openHAB2-start-stop.log` will be generated by starting and stopping openHAB2 inside the Package Manager.