Fix logo link (#381)

Like the rest of the pages of the website, clicking on the pymc logo should go to `www.pymc.io` not to the example gallery

Author: OriolAbril

examples/conf.py

@@ -136,6 +136,7 @@ def setup(app: Sphinx):
             "icon": "fab fa-discourse",
         },
     ],
+    "logo_link": "https://www.pymc.io",
     "search_bar_text": "Search...",
     "navbar_end": ["search-field.html", "navbar-icon-links.html"],
     "page_sidebar_items": ["postcard", "page-toc", "edit-this-page", "donate"],