Add social metadata and sitemap info

Author: DiogoRibeiro7

_config.yml

@@ -81,12 +81,12 @@ baidu_site_verification  :
 
 # Social Sharing
 twitter:
-  username               :
+  username               : diogoribeiro7
 facebook:
-  username               :
+  username               : diogoribeiro7
   app_id                 :
-  publisher              :
-og_image                 : # Open Graph/Twitter default site image
+  publisher              : https://www.facebook.com/diogoribeiro7
+og_image                 : /assets/images/data-science.png
 # For specifying social profiles
 # - https://developers.google.com/structured-data/customize/social-profiles
 social:

robots.txt

@@ -1,5 +1,5 @@
 User-agent: *
 Disallow:
 
-# Sitemap location
-Sitemap: https://diogoribeiro7.github.io/sitemap.xml
+# Sitemap
+Sitemap: https://diogoribeiro7.github.io/sitemap.xml