docs: update 'packages/core-types/src/types/ICredentialIssuer.ts'

[hylim-tech-lover]

What issue is this PR fixing

closes #1356

What is being changed

packages/core-types/src/types/ICredentialIssuer.ts is updated with correct description for type definition

Quality

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• I want these changes to be integrated
• I successfully ran pnpm i, pnpm build, pnpm test, pnpm test:browser locally.
• I allow my PR to be updated by the reviewers (to speed up the review process).
• I added unit tests.
• I added integration tests.
• I did not add automated tests because _________, and I am aware that a PR without tests will likely get rejected.

Details

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