docs: fix invalid JSON in credential offer request examples

[TheSeydiCharyyev]

Description

The credential offer request examples in the DIDComm issuance tutorial contain invalid JSON that does not parse:

• missing comma after "credentialFormat": "JWT" in the JWT example
• broken "id: key (missing the closing quote, should be "id":) inside credentialSchema, in both the JWT and SD-JWT "Current API" examples

These are syntax-only fixes so the examples are valid JSON and can be copied and run as-is. The field structure already matches the CreateIssueCredentialRecordRequest schema; only the literal text was wrong.

Checklist

• My PR follows the contribution guidelines of this project
• My PR is free of third-party dependencies that don't comply with the Allowlist
• I have commented my code, particularly in hard-to-understand areas (N/A — documentation-only change)
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works (N/A — documentation-only change)
• I have checked the PR title to follow the conventional commit specification

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud