feat(docs): Add link to demo in GraphQL api indexes

docs/content/docs/graphql-api/_index.md

@@ -9,6 +9,7 @@ showtoc: false
 This section contains a description of all queries, mutations and related types available in the Vendure GraphQL API.
 
 The API is split into two distinct endpoints: *Shop* and *Admin*. The Shop API is for storefront client applications, whereas the Admin API is used for administrative tasks.
+
 {{% alert %}}
 All documentation in this section is auto-generated from the Vendure GraphQL schema.
 {{% /alert %}}

docs/content/docs/graphql-api/admin/_index.md

@@ -8,3 +8,6 @@ showtoc: false
 
 The Admin API is primarily used by the included Admin UI web app to perform administrative tasks such as inventory management, order tracking etc.
 
+{{% alert %}}
+Explore the interactive GraphQL Admin API at [demo.vendure.io/admin-api](https://demo.vendure.io/admin-api)
+{{% /alert %}}

docs/content/docs/graphql-api/shop/_index.md

@@ -7,3 +7,7 @@ showtoc: false
 # GraphQL Shop API
 
 The Shop API is used by storefront applications. It provides all the necessary queries and mutations for finding and viewing products, creating and updating orders, checking out, managing a customer account etc.
+
+{{% alert %}}
+Explore the interactive GraphQL Shop API at [demo.vendure.io/shop-api](https://demo.vendure.io/shop-api)
+{{% /alert %}}