Update serialization-of-cairo-types.adoc (starknet-io#1307)

components/Starknet/modules/architecture-and-concepts/pages/smart-contracts/serialization-of-cairo-types.adoc

@@ -148,8 +148,8 @@ Consider the following definition of an enum named `Week`:
 [source,cairo]
 ----
 enum Week {
-    Sunday: (), // Index=1. The variant type is the unit type.
-    Monday: u256, // Index=2. The variant type is u256.
+    Sunday: (), // Index=0. The variant type is the unit type.
+    Monday: u256, // Index=1. The variant type is u256.
 }
 ----
 
@@ -162,8 +162,8 @@ Now consider instantiations of the `Week` enum's variants as shown in the table
 |===
 |Instance |Description |Serialization
 
-|`Week::Sunday` | Index=`1`. The variant's type is the unit type. | `[1]`
-|`Week::Monday(5)` a| Index=`2`. The variant's type is `u256`.| `[2,5,0]`
+|`Week::Sunday` | Index=`0`. The variant's type is the unit type. | `[1]`
+|`Week::Monday(5)` a| Index=`1`. The variant's type is `u256`.| `[2,5,0]`
 |===
 
 .Enum serialization example 2