docs: more tips and tricks for custom classes

docs/others/work_with_classes.md

@@ -0,0 +1,37 @@
+# Working with Classes
+
+Custom classes can be assigned to Node as `data` attribute, or any other attribute name.
+
+```python
+from bigtree import Node
+
+
+class Folder:
+    def __init__(self, name: str):
+        self.name = name
+
+    def __str__(self):
+         return f"Folder<{self.name}>"
+
+class File:
+    def __init__(self, name: str):
+        self.name = name
+
+    def __str__(self):
+         return f"File<{self.name}>"
+
+folder_documents = Node("My Documents", data=Folder("Documents"))
+file_photo1 = Node("photo1.jpg", data=File("photo.jpg"))
+file_photo2 = Node("photo2.jpg", data=File("photo.jpg"))
+folder_documents.children = [file_photo1, file_photo2]
+
+folder_documents.show()
+# My Documents
+# ├── photo1.jpg
+# └── photo2.jpg
+
+folder_documents.show(alias="data")
+# Folder<Documents>
+# ├── File<photo.jpg>
+# └── File<photo.jpg>
+```

mkdocs.yml

@@ -59,6 +59,7 @@ nav:
       - others/nodes.md
       - others/merging_trees.md
       - others/weighted_trees.md
+      - others/work_with_classes.md
 
 theme:
   name: material