Install correct node version before yarn install

Updating dev setup instructions to show instructions for installing the correct version of node *before* yarn install. Because `yarn install` keeps failing when using the wrong NodeJS version.

CONTRIBUTING.md

@@ -68,6 +68,14 @@ You'll need the following:
 * [Docker Compose](https://docs.docker.com/compose/install/)
 * [Foundry](https://getfoundry.sh)
 
+### Install the Correct Version of NodeJS
+
+Using `nvm`, install the correct version of NodeJS.
+
+```
+nvm use
+```
+
 ### Setup
 
 Clone the repository, open it, and install nodejs packages with `yarn`:
@@ -78,14 +86,6 @@ cd optimism
 yarn install
 ```
 
-### Install the Correct Version of NodeJS
-
-Using `nvm`, install the correct version of NodeJS.
-
-```
-nvm use
-```
-
 ### Building the TypeScript packages
 
 [foundry](https://github.com/foundry-rs/foundry) is used for some smart contract