Revert "index.rst: don't mention current page under "Other help pages""

Unfortunately this removes the index also from the sidebar in other pages. This makes it basically inaccessible.

Maybe there is a way to not show it in the list at the bottom, but this isn't it. Maybe a manual list of pages instead of reusing the TOC?

This reverts commit b5a95317f0.

doc_src/index.rst

@@ -133,6 +133,7 @@ Other help pages
 .. toctree::
    :maxdepth: 1
               
+   self
    faq
    interactive
    language