FIX: use parent when self is use in a toctree (#938)

* FIX: use parent when self is use in a toctree

* typo in comments

src/pydata_sphinx_theme/__init__.py

@@ -247,9 +247,14 @@ def generate_header_nav_html(n_links_before_dropdown=5):
         meth = "findall" if hasattr(root, "findall") else "traverse"
         for toc in getattr(root, meth)(toctree_node):
             for title, page in toc.attributes["entries"]:
+                # if the page is using "self" use the correct link
+                page = toc.attributes["parent"] if page == "self" else page
+
                 # If this is the active ancestor page, add a class so we highlight it
                 current = " current active" if page == active_header_page else ""
                 title = title if title else app.env.titles[page].astext()
+
+                # create the html output
                 links_html.append(
                     f"""
                 <li class="nav-item{current}">