[3.9] bpo-41224: Add versionadded for Symbol.is_annotated (GH-23861). (GH-24017)

(cherry picked from commit 2edfc86)

Author: andresdelfino

Doc/library/symtable.rst

@@ -156,6 +156,12 @@ Examining Symbol Tables
 
       Return ``True`` if the symbol is local to its block.
 
+   .. method:: is_annotated()
+
+      Return ``True`` if the symbol is annotated.
+
+      .. versionadded:: 3.6
+
    .. method:: is_free()
 
       Return ``True`` if the symbol is referenced in its block, but not assigned