feat: Update doc build and app

docs/docs/getting-started/build-an-app.md

@@ -3,4 +3,110 @@ sidebar_position: 1
 title: Build an app
 ---
 
-TODO: quickstart tutorial
+# Build and publish an app
+Apps let you extend Obsidian with your own features to create a custom note-taking experience.
+In this tutorial, you'll compile a sample plugin from source code and load it into Obsidian.
+
+## What you'll learn
+After you've completed this tutorial, you'll be able to:
+- Configure an environment for developing Jan apps.
+- Compile a app from source code.
+- Reload a app after making changes to it.
+
+## Prerequisites
+To complete this tutorial, you'll need:
+- [Git](https://git-scm.com/) installed on your local machine.
+- A local development environment for [Node.js](https://node.js.org/en/about/).
+- A code editor, such as [Visual Studio Code](https://code.visualstudio.com/).
+
+## Before you start 
+When developing apps, one mistake can lead to unintended changes to your app. Please backup the data.
+
+## Development
+### Step 1: Download the sample plugin
+- Go to [Jan sample app](https://github.com/janhq/jan-sample-app)
+- Select `Use this template button` at the top of the repository
+- Select `Create a new repository`
+- Select an owner and name for your new repository
+- Click `Create repository`
+- Clone your new repository
+- Start developing locally
+
+### Step 2: Initial Setup
+
+After you've cloned the repository to your local machine or codespace, you'll need to perform some initial setup steps before you can develop your plugin.
+
+> [!NOTE]
+>
+> You'll need to have a reasonably modern version of
+> [Node.js](https://nodejs.org) handy. If you are using a version manager like
+> [`nodenv`](https://github.com/nodenv/nodenv) or
+> [`nvm`](https://github.com/nvm-sh/nvm), you can run `nodenv install` in the
+> root of your repository to install the version specified in
+> [`package.json`](./package.json). Otherwise, 20.x or later should work!
+
+1. :hammer_and_wrench: Install the dependencies
+
+   ```bash
+   npm install
+   ```
+
+1. :building_construction: Package the TypeScript for distribution
+
+   ```bash
+   npm run bundle
+   ```
+
+1. :white_check_mark: Check your artifact
+
+   There will be a tgz file in your plugin directory now
+
+### Step 3: Update the Plugin Metadata
+
+The [`package.json`](package.json) file defines metadata about your plugin, such as
+plugin name, main entry, description and version.
+
+When you copy this repository, update `package.json` with the name, description for your plugin.
+
+### Step 4: Update the Plugin Code
+
+The [`src/`](./src/) directory is the heart of your plugin! This contains the
+source code that will be run when your plugin extension functions are invoked. You can replace the
+contents of this directory with your own code.
+
+There are a few things to keep in mind when writing your plugin code:
+
+- Most Jan Plugin Extension functions are processed asynchronously.
+  In `index.ts`, you will see that the extension function will return a `Promise<any>`.
+
+  ```typescript
+  import { core } from "@janhq/core";
+
+  function onStart(): Promise<any> {
+    return core.invokePluginFunc(MODULE_PATH, "run", 0);
+  }
+  ```
+
+  For more information about the Jan Plugin Core module, see the
+  [documentation](https://github.com/janhq/jan/blob/main/core/README.md).
+
+So, what are you waiting for? Go ahead and start customizing your plugin!
+
+## App installation
+![Manual installation](img/build-app-1.png)
+- `Select` the built `*.tar.gz` file
+- The App will reload after new app get installed
+
+## App uninstallation
+To be updated
+
+## App update
+To be updated
+
+## App publish
+After you have completed with local app development and want to publish to `Jan marketplace` for other to reuse, please follow the following steps
+- Update your local `package.json` and configure `npm login` correctly
+- Run `npm publish` and set to public NPM package (so that other can install) - Please refer to our example [NPM retrieval plugin](https://www.npmjs.com/package/retrieval-plugin)
+- Go to `Jan plugin catalog`(https://github.com/janhq/plugin-catalog) and create a `Pull request` for new `App artifact` (which is a renamed version of your App `package.json`) - Please refer to example [retrieval-plugin](https://github.com/janhq/plugin-catalog/blob/main/retrieval-plugin.json)
+- We at Jan will be responsible to review and merge to `main`
+- Once your new app is on `main`, you and other Jan users can find it in `Jan marketplace`