correct wrong values based on old simulation distance suggested value

suggested simulation distance was updated from 3 to 4 some time ago, and this change reflects that by the formula provided in the description.

README.md

@@ -238,28 +238,28 @@ You can make mobs spawned by a monster spawner have no AI. Nerfed mobs will do n
 Good starting values:
 
       ambient:
-        hard: 56
+        hard: 72
         soft: 30
       axolotls:
-        hard: 56
+        hard: 72
         soft: 30
       creature:
-        hard: 56
+        hard: 72
         soft: 30
       misc:
-        hard: 56
+        hard: 72
         soft: 30
       monster:
-        hard: 56
+        hard: 72
         soft: 30
       underground_water_creature:
-        hard: 56
+        hard: 72
         soft: 30
       water_ambient:
-        hard: 56
+        hard: 72
         soft: 30
       water_creature:
-        hard: 56
+        hard: 72
         soft: 30
 ```