Remove notes about subscription being experimental

Author: leebyron

src/language/ast.js

@@ -187,7 +187,6 @@ export type OperationDefinitionNode = {
   selectionSet: SelectionSetNode;
 };
 
-// Note: subscription is an experimental non-spec addition.
 export type OperationTypeNode = 'query' | 'mutation' | 'subscription';
 
 export type VariableDefinitionNode = {

src/language/parser.js

@@ -236,7 +236,6 @@ function parseDefinition(lexer: Lexer<*>): DefinitionNode {
 
   if (peek(lexer, TokenKind.NAME)) {
     switch (lexer.token.value) {
-      // Note: subscription is an experimental non-spec addition.
       case 'query':
       case 'mutation':
       case 'subscription':
@@ -304,7 +303,6 @@ function parseOperationType(lexer: Lexer<*>): OperationTypeNode {
   switch (operationToken.value) {
     case 'query': return 'query';
     case 'mutation': return 'mutation';
-    // Note: subscription is an experimental non-spec addition.
     case 'subscription': return 'subscription';
   }