docs(ui): add note about libreoffice to readme (#992)

src/leapfrogai_ui/README.md

@@ -20,6 +20,12 @@ This document is only applicable for spinning up the UI in a local Node developm
 
 2. Create a .env using the .env.example as a template.
 
+3. Some backend functionality within the app requires libreoffice (for converting files to PDFs). While not required for 
+   the app to run, if you are running the app locally without using the Dockerfile (e.g. via npm run dev), you will 
+   need to install libreoffice.
+
+   ex. ```brew install libreoffice``` or ```sudo apt install libreoffice```
+
 3. Run the Node application and open in your default browser
 
    ```bash