Add Album's and Artist's Stub to diagram

README.md

@@ -192,15 +192,36 @@ class Manager {
 
 }
 
+class StubAlbum {
+    + StubAlbum()
+    + List<Album> GetAlbums()
+    + Album? GetAlbumByUrl(string url)
+    + void AddAlbum(Album album)
+    + void RemoveAlbum(Album album)
+
+}
+
+class StubArtist {
+    + StubArtist()
+    + List<Artist> GetArtists()
+    + Artist? GetArtistByName(string name)
+    + void AddArtist(Artist artist)
+    + void RemoveArtist(Artist artist)
+
+}
+
 
 
 Album --> "+ artist" Artist
-Album --> "- titles" Title
-Playlist --> "- titles" Title
+Album --> "- titles*" Title
+Playlist --> "- titles*" Title
 CustomTitle <|-- Title
 InfoTitle <|-- Title
 InfoTitle --> "+ genre" Genre
 InfoTitle --> "+ artist" Artist
 Manager --> "+ datamanager" IDataManager
+StubArtist --> "- artists*" Artist
+StubAlbum --> "- stubArtist" StubArtist
+StubAlbum --> "- albums" Album
 @enduml