Alphabetize GraphQL API docs fields

https://gitlab.com/gitlab-org/gitlab/issues/198573

lib/gitlab/graphql/docs/helper.rb

@@ -21,6 +21,10 @@ module Gitlab
           MD
         end
 
+        def sorted_fields(fields)
+          fields.sort_by { |field| field[:name] }
+        end
+
         # Some fields types are arrays of other types and are displayed
         # on docs wrapped in square brackets, for example: [String!].
         # This makes GitLab docs renderer thinks they are links so here

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

@@ -21,6 +21,6 @@ fields and methods on a model are available via GraphQL.
     \
     ~ "| Name  | Type  | Description |"
     ~ "| ---   |  ---- | ----------  |"
-    - type[:fields].each do |field|
+    - sorted_fields(type[:fields]).each do |field|
       = "| `#{field[:name]}` | #{render_field_type(field[:type][:info])} | #{field[:description]} |"
     \