feat: update README for migration to monorepo (#165)

This commit updates the README for migration to the SDKs monorepo

README.md

-# Uniswap V2 SDK
+# @uniswap/v2-sdk - Now at `Uniswap/sdks`
 
-[![Unit Tests](https://github.com/Uniswap/uniswap-v2-sdk/workflows/Unit%20Tests/badge.svg)](https://github.com/Uniswap/uniswap-v2-sdk/actions?query=workflow%3A%22Unit+Tests%22)
-[![Lint](https://github.com/Uniswap/uniswap-v2-sdk/workflows/Lint/badge.svg)](https://github.com/Uniswap/uniswap-v2-sdk/actions?query=workflow%3ALint)
-[![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg?style=flat-square)](https://github.com/prettier/prettier)
-[![npm version](https://img.shields.io/npm/v/@uniswap/v2-sdk/latest.svg)](https://www.npmjs.com/package/@uniswap/v2-sdk/v/latest)
-[![npm bundle size (scoped version)](https://img.shields.io/bundlephobia/minzip/@uniswap/v2-sdk/latest.svg)](https://bundlephobia.com/result?p=@uniswap/v2-sdk@latest)
+All versions after 4.3.0 of this SDK can be found in the [SDK monorepo](https://github.com/Uniswap/sdks/tree/main/sdks/v2-sdk)! Please file all future issues, PR’s, and discussions there.
 
-In-depth documentation on this SDK is available at [uniswap.org](https://uniswap.org/docs/v2/SDK/getting-started/).
+### Old Issues and PR’s
+
+If you have an issue or open PR that is still active on this SDK in this repository, please recreate it in the new repository. Some existing issues and PR’s may be automatically migrated by the Uniswap Labs team.