Update links

graphql-c_parser/graphql-c_parser.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |s|
     "changelog_uri" => "https://github.com/rmosolgo/graphql-ruby/blob/master/graphql-c_parser/CHANGELOG.md",
     "source_code_uri" => "https://github.com/rmosolgo/graphql-ruby",
     "bug_tracker_uri" => "https://github.com/rmosolgo/graphql-ruby/issues",
-    "mailing_list_uri"  => "https://tinyletter.com/graphql-ruby",
+    "mailing_list_uri"  => "https://buttondown.email/graphql-ruby",
   }
 
   s.files = Dir["{lib,ext}/**/*.{rb,h,c}"]

graphql.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |s|
     "changelog_uri" => "https://github.com/rmosolgo/graphql-ruby/blob/master/CHANGELOG.md",
     "source_code_uri" => "https://github.com/rmosolgo/graphql-ruby",
     "bug_tracker_uri" => "https://github.com/rmosolgo/graphql-ruby/issues",
-    "mailing_list_uri"  => "https://tinyletter.com/graphql-ruby",
+    "mailing_list_uri"  => "https://buttondown.email/graphql-ruby",
   }
 
   s.files = Dir["{lib}/**/*", "MIT-LICENSE", "readme.md", ".yardopts"]

readme.md

@@ -7,7 +7,7 @@ A Ruby implementation of [GraphQL](https://graphql.org/).
 
 - [Website](https://graphql-ruby.org/)
 - [API Documentation](https://www.rubydoc.info/github/rmosolgo/graphql-ruby)
-- [Newsletter](https://tinyletter.com/graphql-ruby)
+- [Newsletter](https://buttondown.email/graphql-ruby)
 
 ## Installation
 
@@ -34,7 +34,17 @@ Or, see ["Getting Started"](https://graphql-ruby.org/getting_started.html).
 
 ## Upgrade
 
-I also sell [GraphQL::Pro](https://graphql.pro) which provides several features on top of the GraphQL runtime, including [Pundit authorization](https://graphql-ruby.org/authorization/pundit_integration), [CanCan authorization](https://graphql-ruby.org/authorization/can_can_integration), [Pusher-based subscriptions](https://graphql-ruby.org/subscriptions/pusher_implementation) and [persisted queries](https://graphql-ruby.org/operation_store/overview). Besides that, Pro customers get email support and an opportunity to support graphql-ruby's development!
+I also sell [GraphQL::Pro](https://graphql.pro) which provides several features on top of the GraphQL runtime, including:
+
+- [Persisted queries](https://graphql-ruby.org/operation_store/overview)
+- [API versioning](https://graphql-ruby.org/changesets/overview)
+- [Streaming payloads](https://graphql-ruby.org/defer/overview)
+- [Server-side caching](https://graphql-ruby.org/object_cache/overview)
+- [Rate limiters](https://graphql-ruby.org/limiters/overview)
+- Subscriptions backends for [Pusher](https://graphql-ruby.org/subscriptions/pusher_implementation) and [Ably](https://graphql-ruby.org/subscriptions/ably_implementation)
+- Authorization plugins for [Pundit](https://graphql-ruby.org/authorization/pundit_integration) and  [CanCan](https://graphql-ruby.org/authorization/can_can_integration)
+
+Besides that, Pro customers get email support and an opportunity to support graphql-ruby's development!
 
 ## Goals