docs: add proper documentation for the Resource enum (#34)

Author: glihm

crates/contracts/src/world/resource.cairo

@@ -8,11 +8,28 @@ use starknet::ContractAddress;
 /// of re-computing the descriptor each time, which involves several poseidon hash
 /// operations.
 ///
+/// Namespaced resources: Those resources are scoped by a namespace, which
+/// defines a logical separation of resources. Namespaced resources are Model, Event and Contract.
+///
+/// - World: The world itself, identified by the selector 0.
+///
+/// - Namespace: ByteArray
+/// Namespace is a unique resource type, identified by a `ByteArray`, to scope models, events and
+/// contracts.
+/// The poseidon hash of the serialized `ByteArray` is used as the namespace hash.
+///
 /// - Model: (ContractAddress, NamespaceHash)
+/// A model defines data that can be stored in the world's storage.
+///
+/// - Event: (ContractAddress, NamespaceHash)
+/// An event is never stored in the world's storage, but it's emitted by the world to be consumed by
+/// off-chain components.
+///
 /// - Contract: (ContractAddress, NamespaceHash)
-/// - Namespace: ByteArray
-/// - World: The world itself, identified by the selector 0.
-/// - Unregistered: The unregistered state.
+/// A contract defines user logic to interact with the world's data (models) and to emit events.
+///
+/// - Unregistered: The unregistered state, required to ensure the security of the world
+/// to not have operations done on non-existent resources.
 #[derive(Drop, starknet::Store, Serde, Default, Debug)]
 pub enum Resource {
     Model: (ContractAddress, felt252),
@@ -26,6 +43,7 @@ pub enum Resource {
 
 #[generate_trait]
 pub impl ResourceIsNoneImpl of ResourceIsNoneTrait {
+    /// Returns true if the resource is unregistered, false otherwise.
     fn is_unregistered(self: @Resource) -> bool {
         match self {
             Resource::Unregistered => true,