ENGCOM-5460: Declare @doc and @resolver directives #775

 - Merge Pull Request magento/graphql-ce#775 from Vinai/graphql-ce:declare-directives
 - Merged commits:
   1. f653ac8
   2. f25f779
   3. 301ebe7
   4. 24da88e

Author: magento-engcom-team

app/code/Magento/GraphQl/etc/schema.graphqls

@@ -1,6 +1,46 @@
 # Copyright © Magento, Inc. All rights reserved.
 # See COPYING.txt for license details.
 
+directive @doc(description: String="") on QUERY
+    | MUTATION
+    | FIELD
+    | FRAGMENT_DEFINITION
+    | FRAGMENT_SPREAD
+    | INLINE_FRAGMENT
+    | SCHEMA
+    | SCALAR
+    | OBJECT
+    | FIELD_DEFINITION
+    | ARGUMENT_DEFINITION
+    | INTERFACE
+    | UNION
+    | ENUM
+    | ENUM_VALUE
+    | INPUT_OBJECT
+    | INPUT_FIELD_DEFINITION
+
+directive @resolver(class: String="") on QUERY
+    | MUTATION
+    | FIELD
+    | FRAGMENT_DEFINITION
+    | FRAGMENT_SPREAD
+    | INLINE_FRAGMENT
+    | SCHEMA
+    | SCALAR
+    | OBJECT
+    | FIELD_DEFINITION
+    | ARGUMENT_DEFINITION
+    | INTERFACE
+    | UNION
+    | ENUM
+    | ENUM_VALUE
+    | INPUT_OBJECT
+    | INPUT_FIELD_DEFINITION
+    
+directive @typeResolver(class: String="") on INTERFACE | OBJECT
+
+directive @cache(cacheIdentity: String="" cachable: Boolean=true) on QUERY
+
 type Query {
 }