chore: Docs, define additional client-side relations

app/models/Pin.ts

@@ -1,12 +1,26 @@
 import { observable } from "mobx";
+import Collection from "./Collection";
+import Document from "./Document";
 import Model from "./base/Model";
 import Field from "./decorators/Field";
+import Relation from "./decorators/Relation";
 
 class Pin extends Model {
-  id: string;
+  /** The collection ID that the document is pinned to. If empty the document is pinned to home. */
   collectionId: string;
+
+  /** The collection that the document is pinned to. If empty the document is pinned to home. */
+  @Relation(() => Collection, { onDelete: "cascade" })
+  collection?: Collection;
+
+  /** The document ID that is pinned. */
   documentId: string;
 
+  /** The document that is pinned. */
+  @Relation(() => Document, { onDelete: "cascade" })
+  document: Document;
+
+  /** The sort order of the pin on screen. */
   @observable
   @Field
   index: string;