Clarify in the help text that first directory is cloned...

when there is no "template directory" selected/configured.

src/sbbs3/scfg/scfgxfr2.c

@@ -510,6 +510,11 @@ void xfer_cfg()
 						"If you want to clone the options of the template directory of this\n"
 						"library into all directories of this library, select `Yes`.\n"
 						"\n"
+						"If no directory has been configured as the template directory, then\n"
+						"the `first` directory is used as the template to be cloned.\n"
+						"A directory is marked as the template for the library in its\n"
+						"`Toggle Options` menu.\n"
+						"\n"
 						"The options cloned are upload requirements, download requirements,\n"
 						"operator requirements, exempted user requirements, toggle options,\n"
 						"maximum number of files, allowed file extensions, default file\n"