docs: add region support doc to readme [ECO-892]

Author: karantalapalli

README.md

@@ -21,6 +21,7 @@ We have created an in-depth tutorial on how you can create a Vue.js starter webs
 **More Resources**
 
 - [Contentstack documentation](https://www.contentstack.com/docs/)
+- [Region support documentation](https://www.contentstack.com/docs/developers/selecting-region-in-contentstack-starter-apps)
 - [Vue.js documentation](https://v3.vuejs.org/guide/introduction.html)