Added Controls testing + documentation

src/myfasthtml/controls/Dropdown.py

@@ -22,6 +22,12 @@ class DropdownState:
 
 
 class Dropdown(MultipleInstance):
+  """
+  Represents a dropdown component that can be toggled open or closed. This class is used
+  to create interactive dropdown elements, allowing for container and button customization.
+  The dropdown provides functionality to manage its state, including opening, closing, and
+  handling user interactions.
+  """
   def __init__(self, parent, content=None, button=None, _id=None):
     super().__init__(parent, _id=_id)
     self.button = Div(button) if not isinstance(button, FT) else button