Guidebook: Move ladders into stairs section

doc/Guidebook.mn

@@ -1367,7 +1367,7 @@ complete all of the levels according to the traditional rules of
 Sokoban.  Some allowances are permitted in case the player gets stuck;
 however, they will lower your luck.
 .hn 2
-Stairs (`<', `>')
+Stairs and ladders (`<', `>')
 .pg
 In general, each level in the dungeon will have a staircase going up
 (`<') to the previous level and another going down (`>') to the next
@@ -1395,8 +1395,6 @@ and some other monsters will follow along if they're close enough when
 you travel up or down stairs, and occasionally one of these creatures
 will displace you during the climb.  When that occurs, the pet or other
 monster will arrive on the staircase and you will end up nearby.
-.hn 2
-Ladders (`<', `>')
 .pg
 Ladders serve the same purpose as staircases, and the two types of
 inter-level connections are nearly indistinguishable during game play.