doc/update overview section (#904)

* Update overview section

* fix typo

* logomeaning

* Update introduction content

* Update introduction content

* Update suport the project

* typo

* Added linked information

* Finished overview section

docs/docs/overview/technology-stack.md

@@ -2,4 +2,22 @@
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-# Technology stack
+# Technology stack
+
+The app is built with the following technologies
+
+## Frontend
+* [Flutter](https://flutter.dev/) for the mobile app
+  * [Riverpod](https://riverpod.dev/) as state management.
+* [SvelteKit](https://kit.svelte.dev/) for the Web.
+
+## Backend
+* [Nest.js](https://nestjs.com/) for the server.
+  * [TypeORM](https://typeorm.io/) for database management.
+* [PostgreSQL](https://www.postgresql.org/) for the database.
+* [Redis](https://redis.io/) for communication between the core server and the microservices.
+* [NGINX](https://www.nginx.com/) for internal communication between containers and load balancing when scaling.
+
+# App architecture
+
+![Immich Architecture](./img/app-architecture.png)