Add docs to blocks context postprocessing function (#2332)

Co-authored-by: Ian Gonzalez <ian.gl@protonmail.com>

Author: Ian-GL

gradio/blocks.py

@@ -235,6 +235,9 @@ def __exit__(self, *args):
         Context.block = self.parent
 
     def postprocess(self, y):
+        """
+        Any postprocessing needed to be performed on a block context.
+        """
         return y