Review technical content: Desktop Wallet shared accounts - credentials

[TinaKT]

Technical review of the credential management features under "Shared accounts with multiple credentials in Desktop Wallet" to verify technical accuracy and completeness.

Review focus:

• Correctness of all technical information
• Completeness of information
• Removal of irrelevant or redundant information

Review is complete when:

• All technical information has been verified
• Missing information has been identified and added
• Irrelevant or redundant information has been deleted
• PR with necessary changes has been submitted

Pages to review:

1. Shared accounts with multiple credentials in Desktop Wallet: https://github.com/Concordium/concordium.github.io/blob/main/source/mainnet/docs/guides/overview-shared-accounts.rst
2. Create a credentials file: https://github.com/Concordium/concordium.github.io/blob/main/source/mainnet/docs/desktop-wallet/create-credentials-file.rst
3. Add credentials to an account: https://github.com/Concordium/concordium.github.io/blob/main/source/mainnet/docs/guides/multi-credentials.rst

Note: A separate review of language and style will be conducted after the technical review is complete.