update cookies (#59)

mkdocs.yml

@@ -91,10 +91,7 @@ extra:
     title: Cookie Consent
     description: >-
       We use cookies to recognize your repeated visits and preferences, as well as to measure the effectiveness of our documentation.
-      By consenting to the use of cookies, you help us improve the site.
-    cookies:
-      analytics: Google Analythics
-      custom: Essential cookies
+      By consenting to the use of cookies, you help us improve the site. Review the <a href="http://docs.polkadot.com/cookie-policy/" target="_blank" rel="noopener">cookie policy</a> for more information. 
     actions:
       - accept
       - manage