doc: Fix wrong URL for sensitive-data. (#22)

Author: cyrilgdn

website/docs/r/postgresql_role.html.markdown

@@ -22,7 +22,7 @@ same PostgreSQL Cluster, one PostgreSQL provider per database must be created
 and all but the final ``postgresql_role`` must specify a `skip_drop_role`.
 
 ~> **Note:** All arguments including role name and password will be stored in the raw state as plain-text.
-[Read more about sensitive data in state](/docs/state/sensitive-data.html).
+[Read more about sensitive data in state](https://www.terraform.io/docs/state/sensitive-data.html).
 
 ## Usage