feat: add 3d printer docs

src/content/docs/guides/3D Printer/mainsail.mdx

@@ -0,0 +1,18 @@
+---
+title: Mainsail
+description: Web interface for the 3D Printer
+hero:
+  tagline: Web interface for the 3D Printer
+  image:
+    file: https://raw.githubusercontent.com/mainsail-crew/mainsail/6130a0aa1776a138feaab691b9e4b1334b676b79/public/img/logo.svg
+---
+
+import { Aside } from '@astrojs/starlight/components';
+
+<Aside type="tip">Quickly connect to its web page [here](http://printer.lebens-home.net/).</Aside>
+
+# Overview
+
+[Mainsail](https://docs.mainsail.xyz/) is the popular web interface for managing and controlling 3D printers with [Klipper](https://www.klipper3d.org/).
+
+[Source](https://github.com/mainsail-crew/mainsail)