Update Solana README.md to fix errors.

[lubao]

1. add npm i --save-dev @types/node command to resolve error while running npx cdk deploy solana-common command.
   • Error meesage: "Cannot find name process"
2. Retrieve EC2 Private IP Address instead of Public IP Address.
   • the RPC cURL command failed since the NODE_INTERNAL_IP retrieve public ip instead of private ip

What does this PR do?

🛑 Please open an issue first to discuss any significant work and flesh out details/direction - we would hate for your time to be wasted. Consult the CONTRIBUTING guide for submitting pull-requests.

Motivation

More

• [x] Yes, I have tested the PR using my local account setup (Provide any test evidence report under Additional Notes)
• [x] Mandatory for new node blueprints. Yes, I have added usage example to the README.md file in my blueprint folder
• [x] Mandatory for new node blueprints. Yes, I have implemented automated tests for all stacks in my blueprint and they pass
• [x] Mandatory for new node blueprints. Yes, I have added a reference to my README.md file to website/docs section for this feature
• [x] Yes, I have set up and ran all pre-merge quality control tools on my local machine and they don't show warnings.

For Moderators

• [x] The tests for all current blueprints successfully complete before merge?
• [x] Mandatory for new node blueprints. All pre-merge quality control tools and cdk-nag tools don't show warnings?
• [x] Mandatory for new node blueprints. The deployment test works on blank AWS account according to instructions in the README.md before merge?
• [x] Mandatory for new node blueprints. The website builds without errors?

Additional Notes