Improve the documentation for state sharing between contracts

[devendran-m]

Problem Statement (received as feedback from Xrod);

There is no efficient mechanism for state sharing between contracts. If Contract A stores data under its URef, why can’t Contract B access that state directly? Why must Contract A explicitly share some state? If this state can already be read off-chain, why can’t it be accessed on-chain? If there is a solution available for this, it should be prominently mentioned in the documentation.

User Story:

As a developer building applications on the Casper Network,
I want an efficient mechanism for state sharing between contracts and clear documentation explaining its implementation,
so that I can simplify interactions between contracts, avoid redundant steps like explicit state sharing, and achieve consistency between on-chain and off-chain data access.

Acceptance Criteria:

• The Casper Network provides a mechanism to allow Contract B to directly access data stored under Contract A’s URef without explicit sharing.
• If a mechanism already exists, it is prominently documented with clear explanations and examples of how it works.
• The documentation explains why certain states accessible off-chain cannot be accessed on-chain, if applicable, with technical reasoning.
• Code examples and use cases demonstrate how to implement state sharing effectively between contracts.
• Best practices for securely and efficiently sharing state between contracts are documented.
• Developers can use the documented mechanism to implement state sharing between contracts without requiring additional support.