[doc] Fix erroneous backslashes in signatures and names (GH-23658)



The issue being resolved is shown in the 3.10 docs (if you select docs for older versions you won't see a visual glitch).

The newer sphinx version that produces the 3.10 docs doesn't treat the backslash to escape things in some situations it previously did.
diff --git a/Doc/library/asyncio-policy.rst b/Doc/library/asyncio-policy.rst
index 5e69525..ef6a058 100644
--- a/Doc/library/asyncio-policy.rst
+++ b/Doc/library/asyncio-policy.rst
@@ -159,7 +159,7 @@
 
 .. class:: AbstractChildWatcher
 
-   .. method:: add_child_handler(pid, callback, \*args)
+   .. method:: add_child_handler(pid, callback, *args)
 
       Register a new child handler.