docs: create upgrade guide

Author: softbeehive

README.md

@@ -14,7 +14,7 @@ Consider supporting efforts to make this project healthy and sustainable. Thank
 ## Quickstart ⚡️
 
 • [**Upgrade guide**](docs/UPGRADE_V1_TO_V2.md)   
-• [**Docs v1**](https://github.com/ectoflow/vue-stripe-js/tree/v1.0.4)
+• **[Docs v1](https://github.com/ectoflow/vue-stripe-js/tree/v1.0.4)**
 
 ### 1. Install
 

docs/UPGRADE_V1_TO_V2.md

@@ -2,3 +2,51 @@
 
 Upgrading your vue-stripe-js from v1 to v2.
 
+Vue Stripe.js v2.0.0 is a major update that makes changes in default choices due to Stripe.js evolution. It was designed with stability in mind. Your upgrade should be smooth and simple.
+
+## Breaking changes
+
+ES module is the de-facto standard. Vite is expected to drop commonjs support in 2025. Don't upgrade if you use "require" instead of "import".
+
+- added npm type module
+- removed commonjs export
+
+## Features
+- Backward-compatible, old implementations should work seamlessly
+- Payment Element is the new default
+- Better TypeScript support
+- Added new examples for Payment, Card, and Express Checkout
+
+## Upgrade
+
+### Install new version
+```bash
+npm install vue-stripe-js@latest
+```
+
+Test your integration. Major upgrade is finished 🎉
+
+## Optional changes
+
+### Provide explicit type to StripeElement
+
+```diff
+<StripeElements>
+-  <StripeElement />
++  <StripeElement type="card" />
+</StripeElements>
+```
+
+### Remove slot props
+Not needed thanks to provide/inject behind the hood
+
+```diff
+<StripeElements
+- v-slot="{ elements, instance }"
+>
+  <StripeElement
++   type="card"
+-   :elements="elements"
+  />
+</StripeElements>
+```