chore: add version notes file

VERSION_NOTES.md

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+
+# Important Notes for v1, v2, and v3
+
+For more info, check the [CHANGELOG](https://github.com/node-formidable/formidable/blob/master/CHANGELOG.md) on the master branch.
+
+## v1 is deprecated
+
+All `v1` versions are deprecated in NPM for over 2 years. You can find it at `formidable@v1` on NPM, and on [v1 branch][v1branch] on GitHub.  
+We highly recommend to use `v2` or `v3`. Both are already in use by many, especially `v2` which was on `formidable@canary` for 2 years.
+
+- **Status: Not Maintained!**
+- We won't provide support or accept reports on that version.
+- **No Backporting:** bugfixes, security fixes, or new features WILL NOT happen!
+- Please move to at least **v2**! 
+- Try with installing `formidable@v2` and if still have the problem - report!
+
+## v2 is the new `latest`
+The `v2` will be simultaneously on two places for some time - `formidable@latest` and `formidable@v2`.
+The source code be available **only** on [v2 branch][v2branch].
+If you want to use v2, it's recommended to lock and use the v2 dist-tag `formidable@v2`. 
+
+**Main Differences from v1:**
+- Better organization and modernized code, requiring newer Node.js versions (>= v10).
+- A lot of bugfixes, closed issues, merged or closed PRs.
+- **Backward compatible to v1!** Should not have problems, the major version bump is just for ensurance.
+- Better docs, new features (plugins, parsers, options) and optimizations.
+
+## v3 - ESModules, Promises, Monorepo structure
+We recommend to use `formidable@v3` to install, as it uses more modern Node.js Streams, has support for Promises and more stuff.
+You can see more info and track some ideas on [issue#635](https://github.com/node-formidable/formidable/issues/635).
+
+- The source code can be found on the [master branch](https://github.com/node-formidable/formidable) on GitHub.
+- It will be published on `formidable@latest` after some time.
+- Dropping older Node.js versions, requiring higher than v12-v14.
+- Dropping v1 compatibility.
+- Rewritten to ESModules, more optimizations.
+- Moving to monorepo structure, more plugins & helper utils.
+
+[v1branch]: https://github.com/node-formidable/formidable/tree/v1
+[v2branch]: https://github.com/node-formidable/formidable/tree/v2
+[v3branch]: https://github.com/node-formidable/formidable/tree/v3