docs: Add programmatically section

docs/mono.md

@@ -1,3 +1,41 @@
 # Use programmatically
 
-_Coming soong_
+Mono can be used programmatically, it's really useful when integrating it with tools like [PM2](https://github.com/Unitech/pm2), [New Relic]() and more.
+
+Let's see what mono `exposes` as default:
+
+```js
+const mono = require('@terrajs/mono')
+```
+
+Definition:
+
+```js
+mono(dir?: string): Promise<context>
+```
+
+> `dir` is optional, it's where you want mono to start, it will look from `<dir>/conf/`, `<dir>/src/` and `<dir>/package.json`.
+
+The context is an `object` with some useful properties:
+
+- `server`: The node.js server created
+- `app`: The Express.js app instance
+- `conf`: Application configuration object, see [configuration](/configuration)
+- `log`: Log instance, see [logging](/logging)
+- `hook`: Mono hook instance, see [hooks](/hooks)
+
+Example `server.js`:
+
+```js
+const mono = require('@terrajs/mono')
+
+mono(__dirname)
+  .then((context) => {
+    console.log('Mono ready!')
+  })
+  .catch((err) => {
+    console.error(err)
+  })
+```
+
+Then you can run Mono by running `node server.js`.