www: document the need to rejumper expansion box ABC

Document the need to rejumper the expansion box ABC, and include a
link to the manual.

esp32/www/abcmem.html

@@ -25,9 +25,9 @@
 	  <input is="x-box" name="abc.mem.abc80.nvram.22k" />
 	  <span class="help">22-24K (incompatible with TKN80)</span>
 	</label>
-	<p class="help">If simulated NVRAM is present, it is used for
-	UFD-DOS and PUN80 system variables; otherwise up to 320
-	bytes of BASIC memory may be consumed.</p>
+	<p class="nvram,help">If simulated NVRAM is present, it is used for
+	  UFD-DOS and PUN80 system variables; otherwise up to 320
+	  bytes of BASIC memory may be consumed.</p>
 	<label class="ufddos">
 	  <b>UFD-DOS ROM</b>
 	  <input is="x-box" name="abc.mem.abc80.ufddos" />
@@ -56,6 +56,10 @@
 		 conflicts="abc.mem.abc80.smartaid3;abc.mem.abc80.nvram.20k;abc.mem.abc80.pun80.29k" />
 	  <span class="help">16-22K, 28-30K (IEC)</span>
 	</label>
+	<p class="abc80mem,help">If MAX80 is used in a Luxor expansion box ABC,
+	the expansion box needs to be rejumpered to support external
+	  memories on the I/O side of the box.<br />
+	  <a class="seemanual" href="https://www.abc80.org/docs/abc80_bruksanvisning_expanstionslada_abc.pdf">See manual.</a></p>
       </fieldset>
       <fieldset class="abc800mem">
 	<legend>Emulated memories for ABC800</legend>
@@ -64,7 +68,7 @@
 	  <input is="x-box" name="abc.mem.abc800.ufddos" />
 	  <span class="help">UFD-DOS 19 for ABC800 (24-28K)</span>
 	</label>
-	<p class="help">ABC800 needs jumper configuration to access external ROM.</p>
+	<p class="abc800mem,help">ABC800 needs jumper configuration to access external ROM.</p>
       </fieldset>
 
       <fieldset class="reset">