docs: add appwrite (#887)

Author: jdegand

README.md

@@ -478,6 +478,7 @@ become an Angular expert.
 * [ngx-clerk](https://github.com/anagstef/ngx-clerk) - An unofficial project that aims to provide a seamless integration of [Clerk](https://clerk.com) features into Angular applications.
 * [ng-supabase](https://github.com/rustygreen/ng-supabase) - An Angular component library for your [Supabase](https://supabase.com/) project!
 * [zitadel](https://zitadel.com/docs/examples/login/angular) - Secure authentication management for your application. Customize as you grow, with easy APIs and programmable workflows. Focus on growing, your login is in good hands.
+* [appwrite](https://github.com/appwrite/appwrite) - Using Appwrite, you can easily integrate your [Angular app](https://appwrite.io/docs/quick-starts/angular) with user authentication and multiple sign-in methods, a database for storing and querying users and team data, storage and file management, image manipulation, cloud functions, and more services.
 
 #### Builders