create ArticleCOntent model

apple/OmnivoreKit/Sources/Models/ArticleContent.swift

@@ -0,0 +1,22 @@
+import Foundation
+
+public struct ArticleContent {
+  public let htmlContent: String
+  public let highlights: [Highlight]
+
+  public init(
+    htmlContent: String,
+    highlights: [Highlight]
+  ) {
+    self.htmlContent = htmlContent
+    self.highlights = highlights
+
+    print(highlightsJSONString)
+  }
+
+  public var highlightsJSONString: String {
+    let jsonData = try? JSONEncoder().encode(highlights)
+    guard let jsonData = jsonData else { return "[]" }
+    return String(data: jsonData, encoding: .utf8) ?? "[]"
+  }
+}