update readme

Author: JackerNgo

README.md

@@ -1,2 +1,13 @@
 # Share Cart GraphQl
 
+Mageplaza Share Cart Extension supports getting and pushing data on the website with GraphQl.
+
+## How to install
+
+Run the following command in Magento 2 root folder:
+
+```
+composer require mageplaza/module-share-cart-graphql
+php bin/magento setup:upgrade
+php bin/magento setup:static-content:deploy
+```