Port typo correction to new description in default code

ide/templates/ide/initial-bot.lua

@@ -20,7 +20,7 @@ end
 -- with 0, the snake keeps its current direction.
 function step()
     -- there is some info in the "self" object, e.g. your current head/segment radius
-    local own_radius = self.r
+    local own_radius = self.segment_radius
 
     -- your snake needs food to grow
     -- to find food in your head's surroundings, call something like that:
@@ -34,7 +34,7 @@ function step()
         -- distance of the food item, relative to the center of your head
         local distance = item.dist
 
-        -- direction to the food item, in radians (0..2*math.pi)
+        -- direction to the food item, in radians (-math.pi .. +math.pi)
         -- 0 means "straight ahead", math.pi means "right behind you"
         local direction = item.d
 
@@ -60,7 +60,7 @@ function step()
         -- distance to the center of the segment
         local distance = item.dist
 
-        -- direction to the segment, in radians (0..2*math.pi)
+        -- direction to the segment, in radians (-math.pi .. +math.pi)
         local direction = item.d
 
         -- radius of the segment