reconsider directions about adding other users to git-secret repo

[joshrabinowitz]

In
https://github.com/sobolevn/git-secret/blob/master/man/man7/git-secret.7.md#usage-adding-someone-to-a-repository-using-git-secret
we say:

Usage: Adding someone to a repository using git-secret

• Get their gpg public-key
• Import this key into your gpg keyring (in ~/.gnupg or similar) by running gpg --import KEY_NAME.txt
• (more steps follow)

Is this good advice? Should we also be telling them to remove that user's public key from their keyring as the final step?

This issue relates to #699

[sobolevn]

I think importing public keys is fine if you remove it afterwards!
Very good catch! 👍