Docs: add top-level index, refactor according to diataxis

docs/site/manual/index.md

@@ -1,11 +1,34 @@
-# Manual
+# :material-book: Manual
 
-Explore the Clan Framework in detail with comprehensive information on specific topics:
+Instructions and explanations for practical Implementations ordered by Topics.
+
+## Tutorials
+
+**Learning-oriented adventures with a hands-on experience.**
+
+<div class="grid cards" markdown>
+
+-   :material-clock-fast:{ .lg .middle } __Set up in 15 minutes__
+
+    ---
+
+    Create your own clan and get everything
+    running in minutes
+
+    [:octicons-arrow-right-24: Getting started](../getting-started/index.md)
+
+</div>
+
+## Guides
+
+**How-to Guides for achieving a certain goal or solving a specific issue.**
 
 - [Include Machines](./include-machines.md): Learn how Clan automatically includes machines and Nix files.
 
-- [Secrets](./secrets.md): Learn how you can manage secrets
+- [Secrets](./secrets.md): Learn how to manage secrets.
 
-- [Inventory](./inventory.md): Access a distributed and editable version of the NixOS module system.
+- [Inventory](./inventory.md): Distributed and editable version of the NixOS module system.
 
-- [Contribute](./contribute.md): Discover how to set up a development environment to contribute to Clan!
+- [Flake-parts guide](./flake-parts.md): Use clan with [flake-parts](https://flake.parts/).
+
+- [Contribute](./contribute.md): Discover how to set up a development environment to contribute to Clan!