Add additional links (graphql-dotnet#1052)

Just realized I had two more posts laying around which might be of interest for people using graphql-dotnet.

Added links:
- [Generic data loaders for Entity Framework in GraphQL](http://corstianboerman.com/posts/2019-02-12/generic-data-loaders-for-entity-framework-in-graphql.html)
- [ASP.NET Core 2.1 and GraphQL; Adding JWT Bearer validation to subscriptions](http://corstianboerman.com/posts/2018-09-10/asp-net-core-2-1-and-graphql-adding-jwt-bearer-validation-to-subscriptions.html)

Author: corstian

docs2/site/docs/guides/links.md

@@ -4,3 +4,5 @@
 * [ASP.NET Core GraphQL Boxed Project Template](https://github.com/Dotnet-Boxed/Templates/blob/master/Docs/GraphQL.md) - A fully featured GraphQL server project template with lots of optional features built on top of ASP.NET Core.
 * [10 part blog series](http://fiyazhasan.me/tag/graphql-dotnet/) by [Fiyaz Hasan](https://twitter.com/FiyazBinHasan)
 * [Implementing pagination with GraphQL.NET and Relay](http://corstianboerman.com/2019-03-08/implementing-pagination-with-graphql-net-and-relay.html) by [Corstian Boerman](https://twitter.com/corstianboerman) - Article describing the details of implementing cursor based pagination (against SQL Server) and exposing this through connections in GraphQL.
+* [Generic data loaders for Entity Framework in GraphQL](http://corstianboerman.com/posts/2019-02-12/generic-data-loaders-for-entity-framework-in-graphql.html) by [Corstian Boerman](https://twitter.com/corstianboerman) - Article describing the implementation of a generic data-loader using Entity Framework. With this approach most of the complexities related to the data-loader are abstracted away, and can easily be used from resolvers.
+* [ASP.NET Core 2.1 and GraphQL; Adding JWT Bearer validation to subscriptions](http://corstianboerman.com/posts/2018-09-10/asp-net-core-2-1-and-graphql-adding-jwt-bearer-validation-to-subscriptions.html) by [Corstian Boerman](https://twitter.com/corstianboerman) - Authorizing subscriptions works a bit different from authorizing queries and mutations. This article describes in a technical way how to use JWT based authorization on subscriptions.