[JohnKorex]

Summary

• Document that ADMIN_ADDRESS and comma-separated ADMIN_ADDRESSES are combined, and remove the nonexistent ADMIN_TIMESTAMP_UNIT setting.
• Align the API reference with the middleware’s actual SEP-53 payload: METHOD:URL:TIMESTAMP:BODY_HASH, including the /v1 path, query string, body hash, and accepted base64/hex signature encodings.
• Clarify malformed timestamp and authentication error responses.

The README already described the four-part payload; this updates its malformed timestamp description and makes the Environment/API references consistent.

Validation: git diff --check passed. Documentation-only change.

Closes #318.

[Ashborne267]

@JohnKorex please resolve conflicts

[JohnKorex]

@Ashborne267 The documentation conflict is resolved, and the branch is rebased on current main. GitHub now reports no merge conflict. CI is still failing on ReferenceError: sep53Hash is not defined in test/routes/ngoApplications.test.ts; this failure is also present on current main. Could you review the updated PR and advise on the CI failure?