Update further reading section of validiums page

- Added a comprehensive article analyzing the different types of rollups, including newer designs like sovereign rollups (validiums are similar to sovereign rollups with validity proofs and off-chain data availability)
- Added a Vitalik article on exit games for EVM validiums

Author: emmanuel-awosika

public/content/developers/docs/scaling/validium/index.md

@@ -163,3 +163,5 @@ Multiple projects provide implementations of Validium and volitions that you can
 - [ZK-rollups vs Validium](https://blog.matter-labs.io/zkrollup-vs-validium-starkex-5614e38bc263)
 - [Volition and the Emerging Data Availability spectrum](https://medium.com/starkware/volition-and-the-emerging-data-availability-spectrum-87e8bfa09bb)
 - [Rollups, Validiums, and Volitions: Learn About the Hottest Ethereum Scaling Solutions](https://www.defipulse.com/blog/rollups-validiums-and-volitions-learn-about-the-hottest-ethereum-scaling-solutions)
+- [Exit games for EVM validiums: the return of Plasma](https://vitalik.eth.limo/general/2023/11/14/neoplasma.html)
+- [The Practical Guide to Ethereum Rollups](https://research.2077.xyz/the-practical-guide-to-ethereum-rollups)