Add max_toot_chars to API v1

patches/max-toot-chars-api.patch

@@ -19,3 +19,25 @@ index 5ae1099d0..c9c76c700 100644
    def thumbnail
      if object.thumbnail
        {
+diff --git a/app/serializers/rest/v1/instance_serializer.rb b/app/serializers/rest/v1/instance_serializer.rb
+index 99d1b2bd6..b5e6c8185 100644
+--- a/app/serializers/rest/v1/instance_serializer.rb
++++ b/app/serializers/rest/v1/instance_serializer.rb
+@@ -6,12 +6,17 @@ class REST::V1::InstanceSerializer < ActiveModel::Serializer
+   attributes :uri, :title, :short_description, :description, :email,
+              :version, :urls, :stats, :thumbnail,
+              :languages, :registrations, :approval_required, :invites_enabled,
++             :max_toot_chars,
+              :configuration
+ 
+   has_one :contact_account, serializer: REST::AccountSerializer
+ 
+   has_many :rules, serializer: REST::RuleSerializer
+ 
++  def max_toot_chars
++    StatusLengthValidator::MAX_CHARS
++  end
++
+   def uri
+     object.domain
+   end