Exclude subscriptions from GraphQL docs

These are not yet ready to be consumed externally so we exclude them
for now

doc/api/graphql/reference/index.md

@@ -11817,22 +11817,6 @@ Represents the Geo sync and verification state of a snippet repository.
 | <a id="submoduletype"></a>`type` | [`EntryType!`](#entrytype) | Type of tree entry. |
 | <a id="submoduleweburl"></a>`webUrl` | [`String`](#string) | Web URL for the sub-module. |
 
-### `Subscription`
-
-#### Fields with arguments
-
-##### `Subscription.issuableAssigneesUpdated`
-
-Triggered when the assignees of an issuable are updated.
-
-Returns [`Issuable`](#issuable).
-
-###### Arguments
-
-| Name | Type | Description |
-| ---- | ---- | ----------- |
-| <a id="subscriptionissuableassigneesupdatedissuableid"></a>`issuableId` | [`IssuableID!`](#issuableid) | ID of the issuable. |
-
 ### `TaskCompletionStatus`
 
 Completion status of tasks.

lib/gitlab/graphql/docs/helper.rb

@@ -347,7 +347,7 @@ module Gitlab
             mutations = schema.mutation&.fields&.keys&.to_set || []
 
             graphql_object_types
-              .reject { |object_type| object_type[:name]["__"] } # We ignore introspection types.
+              .reject { |object_type| object_type[:name]["__"] || object_type[:name] == 'Subscription' } # We ignore introspection and subscription types.
               .map do |type|
                 name = type[:name]
                 type.merge(