Update check_exchanges.md

[LuckyResearchOrg]

I encountered a runtime error when using wscat due to the use of modern JavaScript syntax (?. and ??) in the https-proxy-agent dependency. This issue occurs on systems where Node.js is installed via APT (such as Ubuntu), which often defaults to an outdated version like v10.x that doesn’t support these features.
For anyone facing the same problem, switching to a more recent Node.js version using nvm solved the issue. Here’s the recommended fix:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash
source ~/.bashrc   # or ~/.zshrc if using zsh
nvm install --lts
nvm use --lts
npm install -g wscat