Say what the include layer exports and what it reads from conf

Plugin/unraid/include/monitor_board.php

@@ -44,6 +44,17 @@
 //   The declaration and the markup are cross-checked at runtime. vv_mon_board_js() ships the
 //   declared ids to the page, which compares them against the cards actually present and flags
 //   either direction — a card in the markup nobody declared, or a declaration with no card.
+//
+// EXPORTS
+//   Declaration  vv_mon_board(), vv_mon_board_cards(), vv_mon_board_total()
+//                — the one array every other function here reads. Change the layout by editing
+//                that declaration, never by editing what follows.
+//   Geometry     vv_mon_rung_min(), vv_mon_rung_rows(), vv_mon_rung_rowdiv(),
+//                vv_mon_absent_class()
+//                — derive the column ladder and each card's span from the declaration.
+//   Emitters     vv_mon_board_css(), vv_mon_absorb_css(), vv_mon_board_js()
+//   Validation   vv_mon_board_check()
+//                — the only one that reports rather than renders; see OPERATIONAL SAFEGUARDS.
 // ═══════════════════════════════════════════════════════════════════════════════════════════════
 
 // The narrowest a card may be drawn. Every breakpoint is a function of this number — see