linknx: add config file

Signed-off-by: Othmar Truniger <github@truniger.ch>

net/linknx/files/linknx.config

@@ -0,0 +1,8 @@
+config daemon args
+        # daemon is started as 'linknx --config=$conf $options'
+        # use 'linknx --help' to get all possible options'
+        #
+        # typical example
+        option conf '/etc/linknx.xml'
+        option options '-w --daemon=/var/lib/linknx/linknx.log --pid-file=/var/run/linknx.log'
+