[Documentation] Write Smart Contract Upgrade Guide

[Abd-Standard]

Description

Document the process for safely upgrading NotifyChain contracts.

Tasks
Explain upgrade workflow.
List prerequisites.
Add rollback procedures.
Include verification steps.

Acceptance Criteria
Upgrade process is reproducible.
Risks are documented.
Guide is contributor-friendly.

[naninu123]

Hello, this matches my skill set.

I've been actively contributing to Stellar projects via GrantFox — from Soroban contract optimization to backend API work and frontend fixes. I know how to scope work to requirements without over-engineering.

Steps:

1. Understand the problem deeply
2. Code the solution following existing patterns
3. Validate with tests and submit

Can start immediately!

[huazhuang80-star]

I can take this on as a focused documentation task. I would first inspect the existing contract layout, scripts, deployment notes, and README, then add a contributor-friendly upgrade guide that covers prerequisites, step-by-step upgrade flow, rollback/fallback procedures, verification checks, risks, and links from the main docs/README where appropriate. I will keep the PR docs-only unless the repository already has a clear docs entry point to update.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign campaign!

@huazhuang80-star's PR #151 was approved and merged by @Abd-Standard.

🏆 @huazhuang80-star: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (83 total points). Track your full progress on GrantFox.

👏 Great work, @huazhuang80-star! Keep contributing to Core-Foundry.