chore: update admin-guide, admin account creation step

[psofiterol]

Updated the admin account creation step of the admin guide. Omitting type and name causes subsequent requests to GET /admin/accounts to return:

{"ts":"2025-03-13T10:21:47.204Z","errors":["key=name, reason=Required","key=type, reason=Required"]}

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	77.03%	3351 / 4350
🔵	Statements	77.03%	3351 / 4350
🔵	Functions	75%	240 / 320
🔵	Branches	87.77%	517 / 589

File Coverage

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Generated in workflow #234 for commit ed35cd9 by the Vitest Coverage Report Action