Help: Fix some broken links in the Gameplay section.

The abilities help topic id structure is intentional, according to
generate_ability_topics() (src/help/help_impl.cpp:514).

data/core/help.cfg

@@ -199,7 +199,7 @@ When you win a scenario, the map grays over and the <bold>text='End Turn'</bold>
     [topic]
         id=recruit_and_recall
         title= _ "Recruiting and Recalling"
-        text="<img>src=help/recruit.png align=left float=yes</img>" + _ "Each side begins with one leader in their keep. At the start of any battle, and at times during it, you will need to recruit <ref>dst='..units' text='units'</ref> into your army. To recruit, you must have your leader (for instance, Konrad in the <italic>text='Heir to the Throne'</italic> campaign) on the keep hex of a <ref>dst='terrain_castle' text='castle'</ref>. Then you may recruit by either choosing <bold>text='Recruit'</bold> from the menu or right-clicking on a hex and selecting <bold>text='Recruit'</bold>. This brings up the recruit menu, which lists units available for recruitment, along with their gold cost. Click on a unit to see its statistics, then press the <bold>text='Recruit'</bold> button to recruit it." + _ "
+        text="<img>src=help/recruit.png align=left float=yes</img>" + _ "Each side begins with one leader in their keep. At the start of any battle, and at times during it, you will need to recruit <ref>dst='..units' text='units'</ref> into your army. To recruit, you must have your leader (for instance, Konrad in the <italic>text='Heir to the Throne'</italic> campaign) on the keep hex of a <ref>dst='..terrain_castle' text='castle'</ref>. Then you may recruit by either choosing <bold>text='Recruit'</bold> from the menu or right-clicking on a hex and selecting <bold>text='Recruit'</bold>. This brings up the recruit menu, which lists units available for recruitment, along with their gold cost. Click on a unit to see its statistics, then press the <bold>text='Recruit'</bold> button to recruit it." + _ "
 
 If you right-clicked on a castle hex and selected recruit, the new unit will appear in that hex. Otherwise, it will appear in a free hex near the keep. You may only recruit as many units as you have free hexes in your castle, and you cannot spend more gold than you actually have on recruiting." + _ "
 
@@ -261,7 +261,7 @@ While most units have three levels, not all do. Occasional units (such as <ref>d
 
 Each unit has a certain number of movement points which are used up when moving into a new hex, depending on the Terrain of that particular hex. For instance, grassland nearly always costs 1 movement point to enter. Exactly how many movement points are spent entering a hex depends on the unit type — in forest, elvish units only spend 1 movement point, most human and orc units spend 2, while horsemen spend 3. You can learn how many movement points a unit requires to enter a certain terrain type by right-clicking on it, selecting <bold>text='Unit Description'</bold>, and then looking at <bold>text='Terrain Modifiers'</bold>." + _ "
 
-Another thing to keep in mind while moving is <italic>text='zones of control'</italic>. Each unit — except for level 0 units — generates a zone of control in the hexes immediately surrounding it, and any enemy unit entering those hexes immediately ends its movement. Learning how to use zones of control to your advantage is an important part of Wesnoth, as only <ref>dst='ability_skirmisher' text='skirmishers'</ref> can ignore zones of control." + _ "
+Another thing to keep in mind while moving is <italic>text='zones of control'</italic>. Each unit — except for level 0 units — generates a zone of control in the hexes immediately surrounding it, and any enemy unit entering those hexes immediately ends its movement. Learning how to use zones of control to your advantage is an important part of Wesnoth, as only <ref>dst='ability_skirmisherskirmisher' text='skirmishers'</ref> can ignore zones of control." + _ "
 
 To see where the enemy can move to during their next turn, press Ctrl-v or Cmd-v. Ctrl-b or Cmd-b shows where the enemy could move, if your units were not on the map to block their progress."
     [/topic]
@@ -363,9 +363,9 @@ The current time of day can be observed under the minimap in the status pane. Fo
 
 • <bold>text='Resting'</bold>: A unit which neither moves, attacks, nor is attacked will heal 2 HP in its next turn." + _ "
 • <bold>text='Villages'</bold>: A unit which starts a turn in a village or oasis will heal 8HP. If the unit is poisoned, the poison will be cured instead." + _ "
-• <ref>dst='ability_regenerates' text='Regeneration'</ref>: Certain units (such as trolls) will automatically heal 8HP every turn. If the unit is poisoned, the poison will be cured instead." + _ "
-• <bold>text='Healing units'</bold>: Units with the <ref>dst='ability_heals +4' text='Heals'</ref> ability will heal each allied adjacent unit, usually <ref>dst='ability_heals +4' text='4HP'</ref> or <ref>dst='ability_heals +8' text='8HP'</ref> per turn, or prevent Poison from causing that unit damage." + _ "
-• <bold>text='Curing units'</bold>: Units with the <ref>dst='ability_cures' text='cures'</ref> ability will cure Poison in all allied adjacent units (in preference to healing, if it has that ability as well)." + _ "
+• <ref>dst='ability_regeneratesregenerates' text='Regeneration'</ref>: Certain units (such as trolls) will automatically heal 8HP every turn. If the unit is poisoned, the poison will be cured instead." + _ "
+• <bold>text='Healing units'</bold>: Units with the <ref>dst='ability_healingheals +4' text='Heals'</ref> ability will heal each allied adjacent unit, usually <ref>dst='ability_healingheals +4' text='4HP'</ref> or <ref>dst='ability_healingheals +8' text='8HP'</ref> per turn, or prevent Poison from causing that unit damage." + _ "
+• <bold>text='Curing units'</bold>: Units with the <ref>dst='ability_curingcures' text='cures'</ref> ability will cure Poison in all allied adjacent units (in preference to healing, if it has that ability as well)." + _ "
 • <bold>text='Advancement'</bold>: When a unit <ref>dst='advancement' text='advances'</ref>, it will heal fully. This can happen as soon as your unit gains enough experience, whether it is your turn or not." + _ "
 
 Resting can be combined with other forms of healing, but villages, regeneration, healing and curing cannot combine with each other: the best option will be used. Finally, units heal fully between scenarios." + _ "