Update README.md with debug instructions (#800)

I got a new computer and had some issues setting up the repo. these instructions show what I had to do to get it working while debugging the installation

Author: chrismaree

README.md

@@ -20,6 +20,8 @@ The latest contract deployments on Production will always be under the `deployed
 
 This repository assumes you have [Node](https://nodejs.org/en/download/package-manager) installed, with a minimum version of 16.18.0. Depending on what you want to do with the repo you might also need [foundry](https://book.getfoundry.sh/getting-started/installation) and [anchor](https://www.anchor-lang.com/docs/installation) to also be installed. If you have build issues please insure these are both installed first.
 
+Note if you get build issues on the initial `yarn` command try downgrading to node 20.17 (`nvm use 20.17`). If you've never used anchor before you might need to run `avm use latest` as well.
+
 ## Build
 
 ```shell