bpo-35054: Add yet more index entries for symbols. (GH-10121) (GH-10171)

(cherry picked from commit 913876d824d969f8c7431e8a9d4610a9a11a786e)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Doc/library/doctest.rst b/Doc/library/doctest.rst
index d463356..a138e68 100644
--- a/Doc/library/doctest.rst
+++ b/Doc/library/doctest.rst
@@ -485,7 +485,7 @@
   to test a :exc:`SyntaxError` that omits the traceback header, you will need to
   manually add the traceback header line to your test example.
 
-.. index:: single: ^; caret
+.. index:: single: ^ (caret); marker
 
 * For some :exc:`SyntaxError`\ s, Python displays the character position of the
   syntax error, using a ``^`` marker::
@@ -695,9 +695,9 @@
 
 
 .. index::
-   single: #; in doctests
-   single: +; in doctests
-   single: -; in doctests
+   single: # (hash); in doctests
+   single: + (plus); in doctests
+   single: - (minus); in doctests
 .. _doctest-directives:
 
 Directives