docs: add google sheets storage implementation reference in readme

Author: mastree

README.md

@@ -10,7 +10,7 @@ API_URL=https://something.com/api/
 ENVIRONMENT=dev
 ```
 > **_NOTES:_**
-> - `API_URL` is referring to the endpoint used to actually access/modify the data.
+> - `API_URL` is referring to the endpoint used to actually access/modify the storage data.
 > - `ENVIRONMENT` can be filled with `dev` or `prod`.
 
 Available API path:
@@ -23,6 +23,20 @@ Available API path:
 - GET http://localhost:3000/wedding/message?page=:page&pageSize=:pageSize
 - GET http://localhost:3000/wedding/message/range?offset=:offset&rangeSize=:rangeSize
 
+## Google sheets storage implementation
+
+I forked my production storage implementation in these public google sheets and appscript link for reference:
+- Storage google sheets [link](https://docs.google.com/spreadsheets/d/1WQaAei843mCgEapI-Ev11O6pRD5W3wtMDljZb7hilMw/edit?usp=sharing) (note: custom script to generate data id exist inside as well)
+- Storage endpoint [link](https://script.google.com/d/1_5qAn7WSTUqnANZgh0KlOMbslwa4la3nGS45PoegDpvz2igAp9No9qEi/edit?usp=sharing)
+
+When using this endpoint, you need to deploy the script to be accessible and then use the endpoint URL as the `API_URL`, for example:
+
+```ini
+PORT=3000
+API_URL="https://script.google.com/macros/s/AKfycbzLx_IdnCXupFaFxqOVN4-0wPk4J-LMEw5g6ROX0RlphEWQb0NcNWI4hQfApcW9gx0K6g/exec"
+ENVIRONMENT=dev
+```
+
 ## Running the project
 
 > **_NOTE:_** this is only a template from NodeJS project creation. To properly deploy this project in **production**, you need to follow the [git submodule's parent](https://github.com/mastree/wedding-site-app) docker command.\