Disable docs linting in autogenerated docs

We shouldn't lint autogenerated docs with the vale
docs linting, as it creates too many warnings for
two docs that can't be easily updated.

doc/api/graphql/reference/index.md

@@ -24,7 +24,9 @@ Fields that are deprecated are marked with **{warning-solid}**.
 Items (fields, enums, etc) that have been removed according to our [deprecation process](../index.md#deprecation-and-removal-process) can be found
 in [Removed Items](../removed_items.md).
 
-<!-- vale gitlab.Spelling = NO -->
+<!-- vale off -->
+<!-- Docs linting disabled after this line. -->
+<!-- See https://docs.gitlab.com/ee/development/documentation/testing.html#disable-vale-tests -->
 
 ## `Query` type
 

doc/development/usage_ping/dictionary.md

@@ -10,8 +10,6 @@ info: To determine the technical writer assigned to the Stage/Group associated w
   Please do not edit this file directly, check generate_metrics_dictionary task on lib/tasks/gitlab/usage_data.rake.
 --->
 
-<!-- vale gitlab.Spelling = NO -->
-
 # Metrics Dictionary
 
 This file is autogenerated, please do not edit directly.
@@ -30,6 +28,10 @@ The Metrics Dictionary is based on the following metrics definition YAML files:
 Each table includes a `milestone`, which corresponds to the GitLab version when the metric
 was released.
 
+<!-- vale off -->
+<!-- Docs linting disabled after this line. -->
+<!-- See https://docs.gitlab.com/ee/development/documentation/testing.html#disable-vale-tests -->
+
 ## Metrics Definitions
 
 ### `active_user_count`

lib/gitlab/graphql/docs/templates/default.md.haml

@@ -17,7 +17,9 @@
   Items (fields, enums, etc) that have been removed according to our [deprecation process](../index.md#deprecation-and-removal-process) can be found
   in [Removed Items](../removed_items.md).
 
-  <!-- vale gitlab.Spelling = NO -->
+  <!-- vale off -->
+  <!-- Docs linting disabled after this line. -->
+  <!-- See https://docs.gitlab.com/ee/development/documentation/testing.html#disable-vale-tests -->
 \
 
 :plain

lib/gitlab/usage/docs/helper.rb

@@ -18,8 +18,6 @@ module Gitlab
 
               Please do not edit this file directly, check generate_metrics_dictionary task on lib/tasks/gitlab/usage_data.rake.
             --->
-
-            <!-- vale gitlab.Spelling = NO -->
           MARKDOWN
         end
 

lib/gitlab/usage/docs/templates/default.md.haml

@@ -19,6 +19,10 @@
   Each table includes a `milestone`, which corresponds to the GitLab version when the metric
   was released.
 
+  <!-- vale off -->
+  <!-- Docs linting disabled after this line. -->
+  <!-- See https://docs.gitlab.com/ee/development/documentation/testing.html#disable-vale-tests -->
+
   ## Metrics Definitions
 
 \