feat: add step removing conflicting hardhat plugins (#245)

# Description

- add step to hardhat migration guide - "remove conflicting plugins"

## Additional context

- some builders forget to do this. Not doing this results in hard to
understand error messages

---------

Co-authored-by: Antonio <[email protected]>

content/00.build/40.tooling/20.hardhat/20.guides/20.migrating-to-zksync.md

@@ -47,7 +47,21 @@ You can learn more about each plugin in the [Getting started section](/build/too
     import "@matterlabs/hardhat-zksync";
     ```
 
-3. Add the preferred ZKsync networks to the `hardhat.config.ts` file:
+3. Remove conflicting plugin imports
+
+   - `@nomicfoundation/hardhat-ethers`: `@matterlabs/hardhat-zksync` includes `hardhat-ethers` extended with with support for ZKsync and non-ZKsync networks.
+   - `@openzeppelin/hardhat-upgrades`:  `@matterlabs/hardhat-zksync` includes `hardhat-upgrades` extended with support for ZKsync and non-ZKsync networks.
+   - `@nomicfoundation/hardhat-toolbox`: this plugin includes `@nomicfoundation/hardhat-ethers` which can cause conflicts. Import necessary
+     components separately excluding `@nomicfoundation/hardhat-ethers`.
+
+   ```ts
+   // import "@nomicfoundation/hardhat-toolbox"
+   // import "@nomicfoundation/hardhat-ethers"
+   // import "@openzeppelin/hardhat-upgrades"
+   import "@matterlabs/hardhat-zksync"
+   ```
+
+4. Add the preferred ZKsync networks to the `hardhat.config.ts` file:
 
     ```js
     networks: {