[Docs] Update docs for dropbox loader (#1158)

docs/components/data-sources/dropbox.mdx

@@ -10,6 +10,16 @@ Ensure your app has the following settings activated:
 
 - In the Permissions section, enable `files.content.read` and `files.metadata.read`.
 
+## Usage
+
+Install the `dropbox` pypi package:
+
+```bash
+pip install dropbox
+```
+
+Following is an example of how to use the dropbox loader:
+
 ```python
 import os
 from embedchain import Pipeline as App