Fix algolia key and sitemap url

Author: devendran-m

static/robots.txt

@@ -2,5 +2,5 @@ User-agent: *
 Disallow: /CNAME
 Disallow: /opensearch.xml
 Disallow: /.nojekyll
-Sitemap: https://docs-redux.melpadden.com/sitemap.xml
-# Algolia-Crawler-Verif: 47EC0D9A31F6D517
+Sitemap: https://docs.casper.network/sitemap.xml
+# Algolia-Crawler-Verif: CE382CF3AA18FA59