docs: Add global variable page

packages/docs/pages/.vitepress/config.js

@@ -189,6 +189,10 @@ export default defineConfig({
               text: 'App',
               link: '/build-integrations/app',
             },
+            {
+              text: 'Global variable',
+              link: '/build-integrations/global-variable',
+            },
           ],
         },
         {

packages/docs/pages/build-integrations/global-variable.md

@@ -0,0 +1,39 @@
+# Global Variable
+
+Before handling authentication and building a trigger and an action, it's better to explain the `global variable` concept in Automatisch. Automatisch provides you the global variable that you need to use with authentication, triggers, action, and basically all the stuff you will build for the integration.
+
+The global variable is represented as `$` variable in the codebase, and it's a JSON object that contains the following properties:
+
+## $.auth.set
+
+```typescript
+$.auth.set({
+  key: 'value',
+});
+```
+
+It's used to set the authentication data, and you can use this method with multiple pairs. The data will be stored in the database and can be retrieved later by using `$.auth.data` property. We use this method when we store the credentials of the third-party service. Note that Automatisch encrypts the data before storing it in the database.
+
+## $.auth.data
+
+```typescript
+$.auth.data; // { key: 'value' }
+```
+
+It's used to retrieve the authentication data that we set with `$.auth.set()`. The data will be retrieved from the database. We use the data property with the key name when we need to get one specific value from the data object.
+
+## $.app.baseUrl
+
+```typescript
+$.app.baseUrl; // https://thecatapi.com
+```
+
+It's used to retrieve the base URL of the app that we defined previously. In our example, it returns `https://thecatapi.com`. We use this property when we need to use the base URL of the third-party service.
+
+## $.app.apiBaseUrl
+
+```typescript
+$.app.apiBaseUrl; // https://api.thecatapi.com
+```
+
+It's used to retrieve the API base URL of the app that we defined previously. In our example, it returns `https://api.thecatapi.com`. We use this property when we need to use the API base URL of the third-party service.