Limit auto-declaration of record types to regRecDevDrv only

Allowing this while expanding DBD files for IOCs can insert other
device supports before of the Base "Soft Channel" ones, making the
other type the default. Adds a note that DBD file order matters.

Fixes lp: #1908305

modules/database/src/template/top/exampleApp/src/xxxSupport.dbd

@@ -1,2 +1,2 @@
 include "xxxRecord.dbd"
-device(xxx,CONSTANT,devXxxSoft,"SoftChannel")
+device(xxx,CONSTANT,devXxxSoft,"Soft Channel")