Add local Soroban prerequisites guide for contributors

[Chucks1093]

Summary
Provide a concise setup guide so first-time contributors can run and test the contract locally without guesswork.

Scope

• document required local tools and versions for Soroban contract development
• include quick verification commands for setup health
• add common setup troubleshooting notes

Acceptance Criteria

• guide is added to contract docs and linked from README or CONTRIBUTING
• a new contributor can follow it to run baseline checks
• troubleshooting notes cover at least two frequent setup failures

Contributor coordination: if you pick this up, reach out in Telegram for updates or clarification: https://t.me/accesslayerorg

[Obiajulu-gif]

@Obiajulu-gif has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I will love to work on this issue

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Congratulations, @Obiajulu-gif! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

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