Fixes 404 on docsearch for GraphQL/Errors (graphql#135)

Author: jonmanzo

site/docs/api-reference-errors/index.html.js

@@ -1,3 +1,3 @@
 var React = require('react')
 var Redirect = require('../../_core/Redirect')
-export default () => <Redirect to="/graphql-js/errors/" />
+export default () => <Redirect to="/graphql-js/error/" />