SCP: Added suggestive clarification to ATTACH help try HELP <device> ATTACH

scp.c

@@ -926,6 +926,8 @@ static const char simh_help[] =
       "3ATTACH\n"
       " The ATTACH (abbreviation AT) command associates a unit and a file:\n"
       "++ATTACH <unit> <filename>\n\n"
+      "Some devices have more detailed or specific help available with:\n\n"
+      "++HELP <device> ATTACH\n\n"
       "4Switches\n"
       "5-n\n"
       " If the -n switch is specified when an attach is executed, a new file is\n"