fix variables link (was pointing to https://graphql.org/learn/queries/learn/queries/#variables so removing the 'learn/queries/' part) (graphql#619)

Author: sunapi386

site/learn/Learn-Queries.md

@@ -126,7 +126,7 @@ You can see how the above query would be pretty repetitive if the fields were re
 
 ### Using variables inside fragments
 
-It is possible for fragments to access variables declared in the query or mutation. See [variables](learn/queries/#variables).
+It is possible for fragments to access variables declared in the query or mutation. See [variables](#variables).
 
 ```graphql
 # { "graphiql": true }