[docs] Add docs to use solana without using react packages

[softwarecurator]

Summary

Please add comprehensive documentation that demonstrates how to implement Solana login functionality without relying on React-specific packages. This addition would greatly benefit developers working with different tech stacks or those who prefer a more framework-agnostic approach.
Suggested documentation contents:

Overview of Solana login process without React dependencies
Required libraries and setup (e.g., @solana/web3.js)

Step-by-step guide for implementing Solana login:
- Connecting to a Solana cluster
- Detecting and connecting to wallets
- Signing and verifying messages for authentication
- Handling user sessions
- Code examples in vanilla JavaScript
- Best practices for security and user experience
- Troubleshooting common issues
- Comparison with React-based implementation (optional)

Benefits:

Increased flexibility for developers using different frameworks
Broader adoption of Solana login across various project types
Better understanding of the core Solana authentication process

This documentation would be a valuable addition to the existing resources and would help developers implement Solana login more easily in diverse project environments.

Link to the related docs page

https://docs.reown.com/appkit/javascript/core/installation#smart-contract-interaction

[sriksm19]

+1

[rtomas]

Hey !! I will be working on this in maybe 2/3 weeks :)

internal: https://linear.app/reown/issue/DR-375/solana-javascript-docs-examples