Fix errors in code of tutorials (#432)

Author: radvea

docs/tutorials/roblox/parenting.md

@@ -7,11 +7,11 @@ or `nil`.
 ```Lua
 local folder = scope:New "Folder" {
     [Children] = {
-        New "Part" {
+        scope:New "Part" {
             Name = "Gregory",
             Color = Color3.new(1, 0, 0)
         },
-        New "Part" {
+        scope:New "Part" {
             Name = "Sammy",
             Material = "Glass"
         }
@@ -123,7 +123,7 @@ local folder = scope:New "Folder" {
         -- state object containing children (or nil)
         scope:Computed(function(use)
             return if use(includeModel)
-                then modelChildren:GetChildren() -- array of children
+                then modelChildren -- array of children
                 else nil
         end)
     }
@@ -152,7 +152,7 @@ local folder = scope:New "Folder" {
 			},
 			scope:Computed(function(use)
 				return if use(includeModel)
-					then modelChildren:GetChildren() -- array of children
+					then modelChildren -- array of children
 					else nil
 			end)
 		}

docs/tutorials/tables/forkeys.md

@@ -51,7 +51,7 @@ local foodSet = scope:Value({})
 
 local prefixes = { pie = "tasty", chocolate = "yummy", broccoli = "gross" }
 local renamedFoodSet = scope:ForKeys(foodSet, function(use, scope, food)
-	return prefixes[food] .. food
+	return prefixes[food] .. "_" .. food
 end)
 
 foodSet:set({ pie = true })
@@ -68,7 +68,7 @@ local foodSet = scope:Value({ broccoli = true, chocolate = true })
 
 local prefixes = { chocolate = "yummy", broccoli = scope:Value("gross") }
 local renamedFoodSet = scope:ForKeys(foodSet, function(use, scope, food)
-	return use(prefixes[food]) .. food
+	return use(prefixes[food]) .. "_" .. food
 end)
 
 print(peek(renamedFoodSet)) --> { gross_broccoli = true, yummy_chocolate = true }