add comment for config

Author: adhami3310

reflex/config.py

@@ -890,6 +890,7 @@ class Config:  # pyright: ignore [reportIncompatibleVariableOverride]
     # Extra overlay function to run after the app is built. Formatted such that `from path_0.path_1... import path[-1]`, and calling it with no arguments would work. For example, "reflex.components.moment.moment".
     extra_overlay_function: str | None = None
 
+    # List of plugins to use in the app.
     plugins: list[Plugin] = []
 
     def __init__(self, *args, **kwargs):