docs: update syntax to append algorithm

[dhoppe]

Summary of Pull Request

You just want to append the algorihm ssh-rsa instead of replacing already existing algorithms.

Otherwise services like GitHub might complain about unsupported algorithms.

➜ git pull
ERROR: You're using an RSA key with SHA-1, which is no longer allowed. Please use a newer client or a different key type.
Please see https://github.blog/2021-09-01-improving-git-protocol-security-github/ for more information.

Type of Pull Request

• This is a bugfix. type/bug
• This is an enhancement or feature. type/feature or type/enhancement
• This is a documentation update. type/docs
• This is a refactoring update. type/refactor
• This is a chore. type/chore
• This is something else.
  Please describe:

Related to Existing Issues

Issue Number: N/A

Test and Documentation Coverage

• Tests have been completed.
• Documentation has been added or updated.

Breaking Changes?

• Yes, there are breaking changes.
• No, there are no breaking changes.

[tenthirtyam]

LGTM! 🚀

[github-actions]

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