[doc] Fix a few margins due to bad markup (GH-23619)



diff --git a/Doc/library/symtable.rst b/Doc/library/symtable.rst
index c9521d6..40c1795 100644
--- a/Doc/library/symtable.rst
+++ b/Doc/library/symtable.rst
@@ -156,7 +156,7 @@
 
       Return ``True`` if the symbol is local to its block.
 
-    .. method:: is_annotated()
+   .. method:: is_annotated()
 
       Return ``True`` if the symbol is annotated.