examples: restored demo to what is described in the docs

examples/demo/stcmd.host

 dbLoadDatabase "../../dbd/demo.dbd"
 demo_registerRecordDeviceDriver(pdbbase)
-dbLoadRecords "demo.db" "PREFIX=demo1"
+dbLoadRecords "demo.db" "PREFIX=demo"
 #dbLoadRecords "demo.db" "PREFIX=demo2"
 #dbLoadRecords "demo.db" "PREFIX=demo3"
 iocInit
-seq &demo "debug=0,prefix=demo1"
+seq &demo "debug=0,prefix=demo"
 #seq &demo "debug=0,prefix=demo2"
 #seq &demo "debug=0,prefix=demo3"