fix social links

Author: gregsdennis

_data/contact.yml

@@ -13,18 +13,18 @@
 #
 - type: mastodon
   icon: 'fab fa-mastodon'   # icons powered by <https://fontawesome.com/>
-  url:  ''                  # Fill with your Mastodon account page, rel="me" will be applied for verification
+  url:  'https://dotnet.social/@gregsdennis'                  # Fill with your Mastodon account page, rel="me" will be applied for verification
 
 - type: twitter
   icon: "fab fa-twitter"
 
 - type: linkedin
   icon: 'fab fa-linkedin'   # icons powered by <https://fontawesome.com/>
-  url:  ''                  # Fill with your Linkedin homepage
+  url:  'https://www.linkedin.com/in/gregdennis/'                  # Fill with your Linkedin homepage
 
 # - type: stack-overflow
 #   icon: 'fab fa-stack-overflow'
-#   url:  ''                  # Fill with your stackoverflow homepage
+#   url:  'https://stackoverflow.com/users/878701/gregsdennis'                  # Fill with your stackoverflow homepage
 
 - type: rss
   icon: "fas fa-rss"