[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/subprocess.rst b/Doc/library/subprocess.rst
index 7f947ef..4ac3f80 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -339,7 +339,7 @@
                  stderr=None, preexec_fn=None, close_fds=True, shell=False, \
                  cwd=None, env=None, universal_newlines=None, \
                  startupinfo=None, creationflags=0, restore_signals=True, \
-                 start_new_session=False, pass_fds=(), \*, group=None, \
+                 start_new_session=False, pass_fds=(), *, group=None, \
                  extra_groups=None, user=None, umask=-1, \
                  encoding=None, errors=None, text=None, pipesize=-1)