[Docs] Ensure per-contract READMEs reference lifecycle/API/deployment sources

[Jayrodri088]

Complexity / points: Medium (150 points) - maintainer label: points-150-medium

PR must include:

• Closes #38 in the PR description
• Tests added or updated where behavior changes
• Docs updated if public API, lifecycle, or deploy steps change
• No unwrap() in production Soroban contract paths (project convention)
• cargo test passes locally; match CI (cargo fmt, cargo clippy -D warnings) when touching Rust

Problem

We already plan to add per-contract README files (Issue 16), and we also plan to add canonical lifecycle docs (Issue 23) plus docs/API.md (Issue 1) and deployment manifest/scripts (Issues 11 and 30).

To avoid fragmented documentation, each per-contract README should be kept consistent and reference the same sources.

Proposed change

Update and verify the per-contract README content and its links after implementing the earlier documentation issues.

Acceptance criteria

• Each contract has a README that includes:
  • a short purpose statement
  • a correct Γò¼├┤Γö£ΓòóΓö¼├║╬ô├╢┬ú╬ô├╢├⌐╬ô├▓┬╝Γö£Γöñ╬ô├╢┬ú╬ô├«├ë╬ô├╢┬╝╬ô├▓┬ÑΓò¼├┤Γö£Γòó╬ô├▓┬Ñ╬ô├╢┬ú╬ô├╢├▒when to call which functionΓò¼├┤Γö£ΓòóΓö¼├║╬ô├╢┬ú╬ô├╢├⌐╬ô├▓┬╝Γö£Γöñ╬ô├╢┬ú╬ô├«├ë╬ô├╢┬╝╬ô├▓┬Ñ^] call sequence (aligned with lifecycle doc)
  • links to docs/API.md and docs/lifecycle.md
  • references to deployment manifest usage (how to find CONTRACT_IDs)
• README examples do not contain secrets
• All internal links resolve correctly (no broken paths)

Dependencies

• Depends on Issue 16 (per-contract README usage guides)
• Depends on Issue 23 (canonical lifecycle doc)
• Depends on Issue 1 (docs/API.md)
• Depends on Issue 11 (deployment scripts) and Issue 30 (deployment manifests)

[Jayrodri088]

Deferred (Wave 1 scope)
Maintainers are focusing this wave on implementation: escrow, invoice-token lifecycle, settlement/payment flows, payment-distributor, tests, and security bugs — aligned with decentralized invoice factoring on Stellar (liquidity for sellers, yield for investors, on-chain escrow/settlement).

Documentation issues will be reopened or recreated in a later wave. If you already started work, comment here and we can link a follow-up issue.