Add warning about GraphQL support removal

developer-guides/graphql-api/README.md

@@ -1,7 +1,6 @@
 # GraphQL API
 
-Rocket.Chat now supports a GraphQL API.
-> **This API is a work in progress, so feel free to test, ask us questions, and submit Pull Requests!**
+> _Support to GraphQL API was removed in version `2.0.0`_
 
 Here are some links that will be useful for the use of Rocket.Chat GraphQL API
 

developer-guides/graphql-api/authentication/README.md

@@ -1,5 +1,7 @@
 # GraphQL API Authentication
 
+> _Support to GraphQL API was removed in version `2.0.0`_
+
 **Note**
 
 > To be able to use the GraphQL API, a login by GraphQL is needed (Tokens provided by REST API are different from the tokens of the GraphQL API).

developer-guides/graphql-api/schema/README.md

@@ -1,5 +1,7 @@
 # GraphQL API Schema
 
+> _Support to GraphQL API was removed in version `2.0.0`_
+
 To see the GraphQL schema of the Rocket.Chat GraphQL API, you should use some GraphQL graphical tool. <br/>
 These tools are able to show the schema, using the [Instropection tool](https://graphql.org/learn/introspection/) of GraphQL.<br/>
 You can use the instrospection queries to show the schema, but by a graphical tool is easier.<br/>

developer-guides/graphql-api/setup/README.md

@@ -1,5 +1,7 @@
 # GraphQL API Setup
 
+> _Support to GraphQL API was removed in version `2.0.0`_
+
 ## General information
 
 In order to be able to use the GraphQL API, this feature has to be enabled by the administrator. In the admin panel,

developer-guides/graphql-api/subscription/README.md

@@ -1,5 +1,7 @@
 # GraphQL API Subscription
 
+> _Support to GraphQL API was removed in version `2.0.0`_
+
 You can subscribe (Websocket protocol) to listen to events, by a GraphQL subscription.
 You should listen the event on the same port defined in the admin panel, in the GraphQL subscription port field. (`General` -> `GrahQL API` -> `GraphQL Subscription Port`)