DocC documentation support (#4)

This PR contains the work done to:
* Documented all the `private`, `internal`, and `public` interfaces on the existing codebase;
* Set the DocC documentation catalog in the project;
* Written the main `Library` article for the DocC documentation catalog;
* Added the documentation tasks in the `Makefile` file.

Reviewed-on: #4
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Sources/Public/Models/Amiibo.swift

@@ -12,23 +12,45 @@
 
 import Foundation
 
+/// A model that represents an amiibo item.
 public struct Amiibo: Sendable {
     
     // MARK: Properties
     
+    /// A game character.
     public let gameCharacter: String
+    
+    /// A game series.
     public let gameSeries: String
+
+    /// The first 8 hexadecimal characters of an identifier.
     public let head: String
+    
+    /// An image link.
     public let image: String
+
+    /// An amiibo name.
     public let name: String
+
+    /// A game platform type, if any.
     public let platform: Platform?
+    
+    /// A release date.
     public let release: Release
+
+    /// An amiibo series.
     public let series: String
+    
+    /// The last 8 hexadecimal characters of an identifier.
     public let tail: String
+    
+    /// An amiibo type.
     public let type: String
     
-    // MARK: Initialisers
-
+    // MARK: Initializers
+    
+    /// Initializes this model from a given payload.
+    /// - Parameter payload: A payload that contains the values for the model.
     init(_ payload: Components.Schemas.Amiibo) {
         self.gameCharacter = payload.character
         self.gameSeries = payload.gameSeries
@@ -48,10 +70,12 @@ public struct Amiibo: Sendable {
     
     // MARK: Computed
     
+    /// An identifier.
     public var identifier: String {
         head + tail
     }
     
+    /// A URL related to an image link, if any.
     public var imageURL: URL? {
         .init(string: image)
     }